Returning of goods.

I Purchase clothing on Saturday when I got home the trousers was to big for my son I return the goods the same day and asked for a copy of the slip, the lady rather told me that they do not have a photo copy all the shops that I return goods to have gives me a copy of the slip how will I be able to return the other clothing if the child come home for the holiday without a slip. The PEP at Eersterust is very unhelpful the community of Eersterus doe snot complain due to most of them does not have emails or smart phones. I need a copy for my SARS return and if I have to return more of the goods how will they be able to assist me without a till slip.