Bad service/attitude

The worst service ever. I bought the 3 for 2 special for jeans on 26 Oct 2019. Then when to exchange the jeans on the 31 Oct and received the worst service ever. I was told as this was a free item I was unable to exchange it, as they don't have the size I wanted. So I asked what I must do with this item as it doesn't fit I was told they don't know as it's my item. I asked can't I exchange it for another item even if I pay the difference cause it's a free item. I was so angry and left the store caus ethey manager was also useless. I left the store without my goods and because it was after hrs couldn't get through to head a office. I then went bakc spoke to the manager again and she had a smirk on her face almost like she was taking me for a fool. Eventually afeer 30 mins or more. I was told I could exchange item for something else of the same pricr. My thing is don't manager have rights to override and does the staff not have customer service s****s. All this infront everyone which made me feel like a fool. The free part of it should never have been an issue. Thsi is terrible service and I just took and item R99 just because I was tired beigg in that store. I Mena I have an account for less than a month with such putrid service. The same service I got when I got to store to open account the same manager was having a sat conversation and I had to wait for Anthony to finish.