Vodacom account **********ly opened on my name!

4 years ago someone **********ly took a contract at vodacom on my name. I have been debited an amoint of R400 per month eversince. I just viewed my bank statement and found that Vodacom has debited R840 on the 1 of February. For the past 4 years an amount of R400 has been debited each month and now it has doubled. This is ridiculous because it is not even my contracts. I have not taken any contracts with Vodacom. I have been sending numerous emails and visited the Vodacom store at the Phoenix branch but nothng has been done. I cannot cancel the debit order via my bank because vodacom will blacklist me and I cannot afford to have a bad credit record. I need this matter to be resolved and my money to be refunded for all these years.