*****ulent Billing

I just found that Vodacom has *****ulent deducted money in my bank account. Vodacom had billed me for the service that did not provide.I had a contract with Vodacom of which I finished paying more than two years ago and early this year I discovered that they are still billing me for the two Simcards that my daughters are using. I then called Vodacom to cancel and change to prepaid, but in some reason I don't know why and how is still *****ulent billing.Vodacom is stilling my money, when I contacted them the consultant told me that it was a mistake from their side. My question is how many customers that are *****ulent billed like this.