Billed for services cancelled due to Immigration

The service of Telkom SA is shocking.We sent a cancellation request(with the necesarry forms completed,with copies of my husbands ID and passport as proof,after the account was settled) through on 22/11/17 as we longer live in South Africa.We received the usual acknowledgement of receipt stating it would take 21 days for the request to be processed.We never heard anything back from Telkom after this email. What makes me livid is the fact that after this email request to them we have received Invoices for December 2017,January and February 2018 now this morning..this means we now owe just under the R2500.00 for services that we cancelled. We now live in New Zealand and are at wits end with this situation,we cannot call them as we no longer have a South African landline to call them from.It seems like this is a common problem with Telkom.We will NOT be paying this amount due as the services was cancelled in November 2017. Kindly sort out this problem or we will be taking this matter further.