Update my account!!!!!

Im frustrated and and angey to say the least, my account is fully paid for as per the 2 installments on the contract, I noticed my account was not updated and that it shows there's a balance same as my installment for the next coming month. I raised a ticked but keep getting this automated robotic response that theres a balance on my account no explanation whatsoever The last time thiss happened I got debuted more than what I was supposed to pay Their customer service agents gave appauling customer service no sense of agency whatsoever