Failed Debit Order - Account in Arrears

I have had a contract with vodacom for nearly 4 years and suddenly last month my debit order failed. My banking details have not changed. I chatted to people in the call centre who assured me that they would resubmit the debit order but it seems that this was not successful as my account is still in arrears. I have done an eft from FNB to avoid my account being suspended. I'm afraid that I might have the same issue at the end of this month. All of my other debit orders are still working fine.