Telkom over charging

I am disgusted and disappointed at telkom mobile. Initially I was very happy with contact I had with telkom I had a s4 mini 100 mins and 5gb of data and I was paying R270. When my 24 months was approaching for my contract to end I enquired about a sim only contract as I was happy with the phone I had. I called up and one advisor advised me that if I leave the contract running month to month telkom deducts the price of phone and I will pay only R99 for contract. I asked her again you sur<br> e because I get 5gb of data and 100 min and she assured me. I called up a month later to another adviser that confirmed same thing. Then December bill came I only paid R99 I was happy. However I got January bill and it showing over R700 all additional charges for my 5gb data? I called call centre spoke to Menzi Magubane manager that said he will try and get charges removed but I must upgrade to avoid these charges in future. I told him that I was told I will only pay R99 for 5gb data and 100 min he said telkom updated him and dont offer it anymore. That is unacceptable and if you offer a customer something you cant change your mind later. I am planning to take this to ICASA if not resolved.