Refusal to Credit account with supporting document

I purchased a fossil watch valued at R2295.00 on my account on 21-12-15. I then proceeded to pay the account in full on the 26-12-15 (R4647.60). I am extremly appaulled by the service i received at the Gateway branch today as the staff ridiculed, laughed and named called me in front of other consumers. I had asked them to credit my account as i no longer wanted the watch due to the seconds needle continuosly stopping. In the same breath asked for my money back as, if logic prevails, they credit my account which is now at zero balance my account would be over paid and that money is due to me as its money that is rightlyfully mine. Verola proceeded to say that they cannot do it.i waited impatiently for half an hour with no reslove to my situation despite the fact that i had all the supporting documentation to prove that i purchased it in their store and paid the account in full. Irate as i am that they refused to do it for they needed authorisation because there was no manager on duty,i yelled and told them the processes they should follow.Renuka began to discriminate against my character and called me rude. i now sit with a watch i do not need and NO resolve to my situation.