Telkom annoying calls

I have a cellphone contract with Telkom, which is paid through a monthly debit order. For reasons unknown to me, I received a call in May stating that I had been handed over to NUDEBT for nonpayment. This is surprising, as the debit order has always gone off as scheduled.

Since then, I’ve been inundated with daily calls and SMS messages demanding payment of an alleged overdue amount of R2,435.48, along with threats of legal action. This has become extremely frustrating and disruptive, especially considering I have upheld my end of the agreement. I would appreciate urgent clarification and resolution of this matter.