Feeling undermined

I bought items on a promotional sale which were buy two get two free. I used and and was not happy with the sizes. When I took the items back to exchange was told I needed to exchange with either sale items or bring back everything and buy those two on normal price. I spoke to Thabiso at Southgate mall. You can just see that they were making me a fool about this incident. I'm really dissatisfied and disappointed because I asked them to then give me a bigger size of those items . They still refuse. Edgars should write a policy at their door in big letters that you are only allowed to exchange sale on sale items.