OFFERS!

Deal/offer/package

Si se trata de un "bono" válido por 50/100 o megas ilimitadas durante un día, parece que se trata de un cupón válido para 50/100 o megas ilimitadas durante un día.

In this context, “bono” is a one-day “supplement” available to users who have consumed the entire monthly quota allowed in their “plan”, before the end of the month. These users can buy a “bono” to fill the gap until the next plan period starts.

The usual English term is “top-up”.

Note that a few mobile companies also (confusingly) use “bono” to mean to (monthly) “plan” – but in Asker’s ST it’s clear from the numerical data that it refers to a daily top-up.

However:
Asker will need to considered whether "Bono 1" (etc.) need to be treated as proper nouns (i.e. untranslateable), where "Bono 1" is the commercial product name of the cheapest "top-up", etc. If that is the case, the names should be left in Spanish and explained in (...) or a footnote.

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Note added at 4 hrs (2017-07-06 14:40:59 GMT)
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Re: coupon / voucher and similar terms

The method used to secure payment of the top-up charge varies from one company to another. Some require the user to buy a prepayment card (coupon, voucher, …) that provides a code to be entered into the company’s website to apply the ‘bono’. Others require the user to log-in to the website and authorise the company to add the bono charge to the next monthly plan bill.

Terms like ‘coupon’ or ‘voucher’ only apply to the first of those methods, so cannot be used here unless it is known that the company doesn’t use the second method (or some other method).

IOW, in the absence of details about the payment method used, the translation of ‘bono’ must be the generic ‘top-up’, which refers to the purpose, and not ‘coupon/voucher’, which refers to specific payment methods.

I recently received a number of text messages from my carrier while I was in the UK using a pay-as-you-go SIM. The term used seems to be either "add-on" or "pack", but I think the relevant one here is probably "add-on", as a "pack" appears to be the term for a kind of PAYG plan that you can renew each month if you have sufficient credit.
I think the reason the term "bono" is used is that they are extra "bundles" that you are eligible for only if you have already opted for a "pack" (which implies you have already topped up your credit by a certain amount first).
So, to summarise, you first buy a "pack", of say 10, 20, 25, 30 pounds, etc., then you will be eligible for an "add-on" for a lesser additional fee.

Here is one of the text messages I was sent after I had topped up my credit enough to opt in to a "pack":

To buy a £5 UNLIMITED minutes, texts and data add-on for 5 days, make sure you have £5 credit, then simply reply YES & we'll add it to your account...

Here's an explanation, this time from another UK carrier:

What are Add-ons?
Add-ons are great-value little packages that help you save money on the things you do most on your device. They can include bundles or units of texts, calls or internet data (depending on which one you choose), and last until your current bill cycle ends and your monthly allowance refreshes, unless you have a long term Add-on that’s applied to your account each month until you ask us to cancel it.
http://support.three.co.uk/SRVS/CGI-BIN/WEBISAPI.DLL?Command...

Vodaphone uses the same term here, though I can't copy and paste the text unfortunately:
https://n.vodafone.ie/shop/pay-as-you-go-plans/add-ons.html

This is from an NZ carrier:
If you need more than what a Combo offers then grab an Add-On with your Combo to make it just right.
You can even mix and match 28 and 7 day Combos and Add-Ons except where there is no additional benefit (such as buying more texts on an Unlimited Text Combo).
https://www.skinny.co.nz/pricing/add-ons/

Looking around I also found the term "bolt-on" is used in the same sense by other carriers:

What are Bolt Ons?

When you're running low on minutes, texts or data, you can top up with a Bolt On, from as little as £3 a month. There are even Bolt Ons for calling abroad, or if you're going away yourself.
https://www.o2.co.uk/shop/tariffs/bolt-ons/

This is another possibility. I suppose it depends on the country.

Pay as you go data bundles | Help & Support | Tesco Mobile
www.tescomobile.com/help-and-support/1082-pay.../pay-as-you...
Pay as you go data bundles. You can choose a bundle from 500MB up to 8GB a month and change it whenever you want. To buy, change or cancel a data bundle just log in to My Account and go to 'My discounts and bundles'. You can also buy up to a 1GB bundle by calling 282 free from your Tesco Mobile phone.

Transatel DataSIM, la tarjeta para tener Internet móvil en el extranjero ...
www.movilonia.com › Noticias
Mar 20, 2017 - Bonos de datos (data bundles). Duran 30 días desde que se activan. Transatel DataSIM permite navegar desde 2 céntimos por MB y también ...

Internet Data Plan, Prepaid/ Postpaid Unlimited Data Plan, Night Shift ...
https://www.safaricom.co.ke/personal/internet/getting.../cho...
Discover, explore and connect with our wide selection of Data bundles available for PrePay and PostPay subscribers, with each offering giving you the best ...

Prepaid Data Bundles | Vodacom
www.vodacom.co.za/vodacom/shopping/data/prepaid-data
Buy Once-off and monthly recurring data bundles for prepaid that suit your needs. Choose between cost-effective recurring or once-off data bundles. ... 1GB, R89, R0.09, R1.50, R1.00. 1GB* (Forthnight), R99, R0.10, R1.50, R1.00. Bundle Size ...