cellucity ripping me off

I purchased a phone on Friday the 30/1/2015 from cellucity galleria. on Saturday morning, I took the phone back , as I had purchased the wrong phone.i asked for a refund as they didn't have the one I wanted.i was told to come back on Monday as the manager that does refunds is not there.my mother then took the phone back on Monday and was told she cant get the money back, she must pick something else from the shop.i want my money back, as there is nothing else I want from that shop and they can take their phone back.its still in its sealed packaging.