Harrasment for undue debt

I last had a telkom account over 2 years ago. When they duplicated charges and was unable to get it sorted, i closed my account. I'm now been harrased by MCS for payment of an utstanding Telkom account. They can't tell me what account it is or how much is outstanding. I have correspondence for telkom confirming that i owe them nothing.

MR/S WHITAKER

Ref No: TELK***8

YOUR OUSTANDINGTelkom MCS Account

Your outstanding Telkom account has been handed over to MCS Debt Recovery for collections. It is in your best interest to pay the full outstanding balance due.

To avoid any further action on your account, please adhere to the following:

•Contact our offices on *** for assistance with a payment plan as soon as possible to avoid any further legal proceedings or •Make immediate payment via bank details provided below .

So how the hell can one sort this out