Accounts department extremely poor.

Accounts department extremely poor. I tried to consolidate my 6 months plan with my 12 months to make all over 12 months. I was told it was fine and given an amount to pay. To my surprise, when I receive the invoice for June, it shows I'm in arrears and I am getting called my financial services. Further, I have never requested the 6 month option, but the cashiers don't even ask sometimes and just choose whatever. I will definitely close this account due to poor service.