If you do make a claim and are successful you may find that the creditor in question keeps this money to offset against their debts. If they don't, then you will be expected to pay this money across to your IVA.
Either way it means your creditors will get a better dividend.
Sharing from experiences of dealing with debt
The greatness of a man is not in how much wealth he acquires, but in his integrity and his ability to affect those around him positively.
Bob Marley. http://kallis3.blogs.iva.co.uk
My claim was made personally directly to Lloyds. They ignored my letter so I went up the chain to the Finiancial Obundsman.
For some reason they then did respond and I got £4K back. Was knocked straight off my balance, but it felt good! If I had needed to pay anyone, I would have been well out of pocket. Total cost, few sheets of A4, couple of stamps and envelopes!
Also made it easier to put a F&F forward, as I eneded up with around £6.5K knocked off my "owed" amount show in my original IVA documents.