FREE upgrade = R254 per month !!

Earlier this year I received a phone call from a Telkom representative offering me a FREE upgrade from 4Mbps to 10Mbps on my fibre line. I, of course, accepted and, sure enough, my line speed was increased. I continued to pay the price of a 4Mbps line until three months ago when, out of the blue, my account was increased by R254 per month. I raised a dispute with Telkom three months ago and another dispute two months ago and another dispute last month. I now have a account that is arrears to the tune of R750 and three dispute references. Telkom are still asking me for R254 more each month. I did not ask for the line speed upgrade and expected Telkom to honour their promise of a FREE upgrade.