Når du forlanger et ordentligt stykke arbejde
(when you insist on having it done properly)

Når du forventer, at det gøres ordentligt
(when you expect it to be done properly)

Fagmanden, der ved, hvordan det skal gøres
(The expert who knows how it should be done)

The sort of thing that appears in the local newspaper when you look for a builder or electrician.

But your own suggestion, Når du vil have det gjort rigtigt!
is good too.

This would be my suggestion.

I think "right" is best translated as "ordentligt" (properly) in this context - as Christine also has suggested - since "rigtigt" in Danish sounds more like "right" as the opposite of wrong. Here the meaning is more that the work is done in a satisfactory way as I read it.

I would also choose to make it impersonal and omit the "you" in Danish, but otherwise the offered translation could also just be changed to "Når du vil have det gjort ordentligt!".

I am providing a suggestion which I think is more "catch phrasey" which is what I think the German version suggests that this should be; there is a repetition of words and a hint of play on words in my Danish suggestion.
My suggestion is based on the German version which I think is more "catchey".