is it the original company? or is it DCA taking the piss?
if you have the receipt good,if not it dont matter to much
if its a piss taking DCA notify them you have a receipt stating the debts cleared,it is also statute barred and you would like to see their deed of assignment or certified copy and tell them you have received no notice of assignment, and that you are fully prepared to take them to civil court for fraudulent and frivolous claims of which they have no first hand knowledge.
tell them if they cannot respond will the information you asked for and valid proof of claim within 14 days,they agree that they owe you £200 compensation and administration fee.
you might make some money out of this