exchange of goods

I bought a pair of jeans for my granddaughter which were too small. I took them back on Saturday with the tag attached but no slip - I paid R89.99 for them. I only wanted to exchange them for a bigger size. The Manager would not even consider it without a slip and his attitude left a lot to be desired. I think he needs to go on a Customer service course to teach him to speak to people with respect. I had just exchanged a pair of tights at Woolworths with no slip, just the broken cardboard binding with no problem at all. I had to buy another pair of jeans and wasted R89.99 - I didn't buy at Jet and wont again. Unfortunately I didn't get his name