Unable to do an exchange. Unpleasant experience

Good day

I ordered a duvet set and it was delivered on the 12th of April and then i later realized i bought a wrong size. I want a Queen size not a double bed.

So on the 26th of April i went to the branch at Tembisa Mall to exchange the size and the Sales Consultant refused to assist and gave me an attitude. I am now sitting with a duvet that i am unable to use. I just want an exchange with a bigger size. I have sent emails but no one is getting back to me.