bad service experience again(4th time)

Yet another issue I'm faced with by Telkom, this month I have to pay R813.00 where I normally pay R650.00 apparently this is because my billing cycle has changed as well as a increase that I'm not aware off this is almost 200 more. The billing department is saying they can't correct my billing amount and that I have to make the full payment of R813.00 for it to be back to normal next month. If I don't make this payment it will be seen as a short payment and I will be penalized. This is ridiculous, I'm going to look for a different service provider!!