WORST CUSTOMERS SERVICE I HAD WITH ANY ISP

Rain once again and i am sure everybody at rain is aware of their bad customer service. Every month my invoice is incorrect. my payment last month was 1100 + but was fixed to the correct 559 , again this Month 709 , how do you get to these figures why are you robbing people like this. please advise i am again offline, I am working from home so i cant not be offline, i want to be connected so i can atleast search for another internet provider. but Billing service bad customer service but works well when working,, and your new call center is 100 worst than in SA