DMC
No response about 'debt'

I received a visit from debt collectors claiming I owed money on a cell c account that I closed and paid off at least 5 years ago, so I phoned DMC to tell them that I do not acknowledge the debt, have never received a summons and as it has been over 3 years anyway the 'debt' would have prescribed. They then told me to get an affadavit and email it to them which I did, along with a request to please acknowledge receipt of the email and let me know the outcome, and I have still not received any kind of response from them.