DMC - Prescribed debt and no proof of debt

I am so upset with DMC debt collectors. They are now phoning me at my workplace, and we are not allowed any calls at work. They cannot send me proof of my contract, proof of the outstanding debt, proof of date of default, breakdown of all the costs and interest or that the debt has not been prescribed. They are trying to collect on a Virgin Mobile account which I cancelled after the 2 yrs. This contract did not run after 2010 yet in 2015 they started phoning and harassing me. I do not acknowledge the debt and have not acknowledged this debt. As far as i am concerned this debt is prescribed unless they have written or verbal proof that i have acknowledged this.

I want this filed closed with immediate affect, and no more harassment to take place. I will be reporting you to the Council of Debt Collectors if this harassment does not stop.