Data account

After Vodacom offered us a modem with 10gb data daytime and 10gb night owl, we accepted. Within the 1st week our phones reflected that the data was depleted. Every month when the data is finished we can't use it, if we don't top it up. The 2nd month an amount of R4000 was debited towards our bank account. According to Vodacom we requested an open line. WE NEVER DID. Now every month all our phones on this contract gets disconnected cause we are in 'arrears'. They promise to send the voice recording, which never happens. How can they ***** from a person like this??????