Cut off line long before due date every month

This is the third month in a row I have been cut off before my due date on my payment. Originally I didn't even have my line with Telkom directly. We moved to the house next door changed all our details everywhere and suddenly I owed Telkom money. Every month they just keep adding costs and cutting my line long before the due date on the payment. Due to my freelance work I need specific dates for payment so I can make sure there is adequate funds in my account. This is unacceptable. Every month Telkom adds about 100% interest on these payments. How does anyone give there support to a company like this? Oh yes, I do not have a choice apparently...