Dissatisfied

Was at Ackermans in Benoni (Voortreker Street) taking out my layby. Inside the layby I want to return kids mini briefs which I no longer needed, and it so happened that the first slip I did the layby with I did not have it at hand. The cashier that helped me said I need to have that slip without even mentioning the fact that do hygiene purposes its not allowed to return under wear. I'm dissatisfied by this because the shop also have the same copy I have from the first day of layby and fail to understand why was I not assisted in this regard. Called the shop and spoke to some lady who explained why the slip is needed but still goes back to say the shop has an identical slip as myself therefore one can see how much the item was at the time. Now I'm stuck with briefs I do not need, I'm not happy with this... Or at least mention to that underwear is not supposed to be returned, I would have maybe postponed taking out the layby. Cashier name Mathintha Seete (as in slip)