Calling everyday and charging 18 per call, whilst they are holding back on information on MTN bill

I have been called everyday by this company and I have sent emails for the last 2 years requesting information on the R13 000 I supposedly owe MTN who I know I only owed R2000 and the line was suspended after that amount wasnt paid. It is also MTNs fault because I cancelled the contract, and the chose to not cancel it and extract the monthly installment until I stopped paying. I have asked for a statement from SSD to ask MTN to show how 2000 grows to R13000 which is what they say was the handover amount but I have not been sent this statement, instead I have received a statement from SSD which shows how in the past 2 years the R13000 grew to R16000 due to the R18 they charge you everytime they call you for no reason. I had been paying R100 a month for about 2 years and I quit because I am still waiting for the MTN statement, now they are calling me 3 times a day, and its R18 everytime. I have spoken to everyone to sort this out, even MTN is not helpful but this company is really bad.