Advise on installment increasing

Last week i went to Telkom in Bellville to enquire about my monthly installment for my contract phone that keeps on increasing every month. When i signed the contract, it was going to debit a fixed amount of R239, and all of a sudden it increased to R321. Can you explain to me whats happening. You need to be transparent with your customers and not just decide to increase the installment. <br> <br> When i was in Bellville, the consultant did call the call centre but the guy on the phone told me their lines were down and that i must call back again. Which i didnt have a chance. So please Telkom call me back. I want someone who will explain to me whats going on with my contract phone.<br> Thank you