Did an exchange and got the same product

I ordered sandals they delivered the wrong size and I requested an exchange for the right size.

Today I get the exchange pari on to find out its the same pair and on my side like the first time i was receiving the right size.

I called one of their useless agents and he said I must do a refund and I bought the item on discount , so if I want another pair i must now pay full price what kind of nonsense is this.

Its not my fault that they delivered the wrong thing twice, the least they can do is give me an option to pick another shoe and they will cover the balance, since they chose to send me the same things twice.