Collecting Bad debt written off - Prescribed debt

After receiving no contact from Standard Bank or MBD Attorneys since 2014, all of a sudden now I get phoned for debt that already on my ITC report states bad debt written off. If written off why all of a sudden the call to collect the debt? This is ********. Debt has prescribed. If they want me to give them the definition for this, I will gladly do so. Wake up MBD!!!!