direct debit

We have move from RSA in 2002. We have a monthly direct debit that is taken from our bank account in south africa. we do not have a phone line anymore. We have tried several times to cancel the direct debit (through our bank as well as through Telkom) , but with no success. It will be cancelled for a few months, but then they take all the missed payments in one go. Last time they said that there is no active account to which they can link these payments. they think the account was closed, but the instruction not stopped.<br> How can they take payments if there is no account?????