Bad service from Cell C

I took a contract with Cell C in 2018 May, now 2years has gone by meaning it's either I upgrade or i cancel the contract. I gave Cell C a one month termination notice which started on the 6th April 2020,until May8th, 2020. I've been receiving smses stating that my cellphone number has been migrated from a contract number to one of the prepaid products(megabonus). On the 1st of May 2020,I received th monthly benefits, i.e. The minutes, sms and data for the month. But along the weeks the smses were taken off the monthly benefits. I didn't notice it, up until i was sent a msg that some of the benefits will be reduced. Fine they've taken away the smses and the minutes all of them. What frustrates me is they debited my account with a full amount for some of the services they didn't render to me. When I called them no one can answer me, of why was debited the full amount. This is not the first case i have a complain with Cell c, the first complain i laid with them, no one gave me an update to the matter. I was only given a reference no. What kind of a company is Cell C, if they are only good at ripping people off?! M sorry guys but I am not happy with any service that I am receiving from Cell c.