Just send a copy of any debt comms received to your IP, scribble on it the name of the original creditor and state already in IVA with the name of the firm it is filed as in your IVA agreement, ask the IP to tell the creditor to stop contacting you - keep original yourself.
In order to stop the harassment quicker You might want to have a standard letter printed off that has the references blank and you just hand write them in and post if you get chased by any creditor within your IVA . Google shows Sample letters here
http://www.harringtonbrooks.co.uk/suppo ... te-letters
You might want to add a line that says something like proof of this debt was submitted to the IP by <original debtor> And this can be confirmed with the IP.
You have now been made aware the debt you are pursing is subject to an IVA.
Any further demands//statements with myself regarding this matter will be deemed to be harassment from a creditor who is bound by the IVA terms, even if you have acquired this debt from an original creditor. Please do not contact me again regarding this matter or I will be required to advise the appropriate regulators.
Bla bla bla have a nice day