My dictionaries give complaint as well as return for 'reklamation', and this is what many people call them.

Lyng Svensson gives 'complaints rule' for reklamationsregel, but this is a slightly narrower concept.

If the tone of the document allows, I might write 'Handling complaints' or 'Settling complaints' as the title.

As it is store policy that presumably aims to be friendly to the customers and give them the benefit of the doubt, rules have to be set out in a 'gentle' tone, but you do have to be true to the original, as it is basically dealing with the parties' legal rights too. But the title might just give scope for a hint of friendliness.