*****ulent Billing and extremely poor service

i have a contract with Telkom for a phone and a router, Telkom decides to put my account on collections when I've never missed a payment in turn they start deducting ridiculous monies which are not even aligned with my contract amount , my debit date is the 5th of every month they debit on random dates which is not dates we agreed on, the amounts??? Right now my credit report shows im on arrears creating a negative balance whereas i have no outstanding payment towards my contrat im fedup with telkom this is not the first time i addressed this and it still happens. Can i also mention times they suspend my services in the middle of the month saying ive reached my spending limit which i didnt!!!!!