Account in arrears shows no manual payments made

I have a landline/wireless Telkom home account which keeps on accumulating and shows that that I am in arrears. This is despite making manual payments at PnP EasyPay on a monthly basis for which I have proof of payment. On Tuesday the 15th May 2018 I received an sms stating my name and an account number that does not correspond to the current account that I have. It states that this account number, in my name, '...has been handed over to NuDebt Collection due to a default of R833.44'. Thus, this concerns me on two levels: 1) my monthly statement on my actual account keeps on indicating that I do not make monthly payments; and 2) I have been handed over to debt collection for an account on my name but an account I know nothing about. This has to be attended to ASAP. I would appreciate it if a representative can contact me urgently. I have emailed Telkom but to no avail.