jammesbear, i wish i could help you with this but unfortunately i don't have the knowledge or skills. One of the experts will hopefully pick up on this and will be able to advise you on the course of action to take.
My RBS debt was definitely included within my original IVA (as I included absolutely everything at the time) - although I can't rememember who it was collected by. This is the problem that I now have but I am sure it was FMC and the amounts on the list of creditors are almost identical! Surely, DFD would have a note of this somewhere but when I spoke to them this week, they said it would take at least a week to get my paper file up from storage.
I will give them another call tomorrow and let you know. When I spoke to them last the only info relating to the FMC creditor said "for home improvements" and nothing about RBS!