I did not upgrade from samsung note 4 to samsung s4

I received an invoice on the 5th of April from Telkom mobile and the invoice showed that I had upgraded from a Samsung Note 4 to Samsung S4 on the 11th of March 2016 (My word, who would do such? do you even have the S4 in stock?). I called telkom mobile to rectify the mistake and they said that the matter would take a maximum of three days to resolve and they gave me a case number ***0. Telkom mobile never kept their word. After contacting Telkom on numerous occasions to rectify the mistake, I was told the same thing, " the case was assigned to an agent and they would contact me within next 24 hours". I called them again today and it was the same story. It seems like Telkom is not willing to help me out on this one. last month I was billed more than I would normally pay on a monthly basis and when they debited my bank account they did not wait for any agent. Telkom has given me nothing but a poor service here, even their network is ****, the thought of being for another 24 months on telkom mobile is killing me more than anything. I did not request for any phone nor and upgrade. please telkom rectify the mistake.