Telkom trying to ***** my money!!!!!

Telkom delay invoices, make wrong changes to products and doesn't do what customers ask for just so they could after a while hit you with an outrages charges its a ridicules company to say the least my 10mb adsl contract started in January 2018 after 3 months they asked me if i wanted to upgrade to a 20mb line i said yes and they started the process after alot of speed test and phoning them constantly they advised me that i cant get 20mb line speed only 16mb and they said i still had to pay for a 20mb after which i said they must revert my line back to 10mb now after about 6 month they started sending me bills stating first R6000 in the minus then a month later I now owe them R6000 what is wrong with this company i am not going to give them a cent and if they want to stop my line go ahead I will rather take R6000 and get a wireless connection from a different company who wont try to ***** my money a company who's staff is competent enough to resolve queries and do as the customer ask this is probably the worst mistake i ever made was to do bussiness with these clowns.