Complain to Cotton On

COTTON ON boksburg PALMS center. I used my store account for the first time. The lady just swiped my card and didn't ask me for how many months I wish to pay, after I realised this I went back and asked her and her reply was that the system doesn't ask it just pays . This was two weeks ago. Today I went to cotton on menlyn in pretoria, when paying ,the lady asked me for how many months I wish to pay of which I chose 6months. My complain is I don't want to pay interest this is a promotion from cotton if you pay in 6months .now that tall lady with a blond hair cut **** to me and inconvenienced me. She is so unprofessional and I don't like her service at all. Cotton on fix my account to be strictly 6months or i will just pay off and close this account.