Westside - Charged for carry bag which i didnt buy

On april ** I bought things from westside and they charged me ** rupees for carry bag which I told them later that I don't need it and they missed to cancel it. When I went today april ** I went to exchange a belt and that time only I noted it and when I asked them the staff who billed my things yesterday said like it was just a mistake and they will refund me ** rupees. Its not about the money, the staff behaviour towards customer is not good and yesterday she missed to remove the tag from my belt I purchased that is also one of the reason for me to go today here itself. I have never expected this kind of behavior from a reputable brand like westside.
Please review and do the needed action and I want my refund back