Look David, do yourself a favour and take control of your money. Don't let debt collection agencies treat you as a cash cow. In order for a DCA to collect from you, there is a statutory requirement that they have the necessary documentation concerning the debts in their hands. If they do not, they cannot collect. Given that these debts originated with your wife, you certainly should not be paying them.
I won't go into detail here about what you need to do, but I seriously suggest you join the following forum and tell them what you've told us:
http://www.consumeractiongroup.co.uk/forum/forumdisplay.php?167-Debt-Collection-Agencies
They will help you deal with this situation and tell you exactly what to do. Take control of your own money. No doubt you've worked hard for it so please don't give it away to these parasites.