KEEP DEBITING AND NO SERVICE

ive got a wi fi contract with Telkom I signed up for 20 mbps, after few months in the speed dropped and wi fi used to switch itself off I logged online queries as the call centre is impossible to get through i was told to log on and change the settings of which I did and still no luck at this stage the speed was at 1 - 2 mbps from 20, that's ridiculous I sent emails called the call centre only for the calls to keep cutting I myself work in a call centre and have never come across a call centre with such terrible service that's worst than government. no responses to my emails I than reverted to reversing the debit order. after reversing 2 months of installments I get an invoice of which I rep**** to saying just cancel this contract I get a call from their consultant telling me that they cannot cancel as I need to pay the outstanding amounts first and than log to their office for a technician to have it checked of which I refused, they just want to get money out of us and not provide the service. why could they not send a technician out from start of my complaints. they have suspended the line but still keep debiting my account.. THE SERVICE IS RIDICULOUS KEEP TAKING MY MONEY WITHOUT PROVIDING THE SERVICE