Taking clients for granted with their senseless refund policy

My friend was celebrating her new house, and I decided to buy her a diffuser at Coricraft at Mall of Africa on the 25 of Jan, unfortunately my friend told me that lately she can't stand the smelling I guess it's preganancy, I did not even open it since i knew that then i will have to take it back, it is still sealed and I have the original slip so I took it back to Coricraft Centurion wow, I was told this and that, they don't take back diffusers hehe hehe 7 days already passed yooo like it was a lot and finally the lady called the manager who said they will credit me however they can't give me cash I have to buy something from the shop, so my question to Coricraft is if I bought something and it still in a good condition, never used or whatsoever why is it so hard to refund my money back as you took back your diffusser, the lady even told me I had to use the credit before end of this week what if I don't get a chance to step by your shop, what if there is nothing to buy so what is going to happen? Since you can't give me my money?