Billing

As I finished my contract with Telkom in October 2015, I was advised that I'll only pay R99 for 1G data and 100 minutes. instead they keep on billing me for the data of which I never requested and after several contacts with them still they keep on deducting huge amounts of R833.69, R467.19, R548.75, besides the R99 that I pay them every month. this is so disturbing and unprofessional to just budge in my bank account any day of the month. I have a list of reference numbers (26 & 30 Nov ***6, 15 Dec ***6, 6 Jan ***0 & 12 Jan) as a promise to resolve this but nothing has happened till to date. I've sent the cancellation but no response, so what more can I do now.