They are duty bound to put the offer forward. However, I would hope that the reason for all the hoop jumping is so that they can prepare a robust case on your behalf.
I don't think it's a case of them wanting to keep the IVA going just for the fees, to be brutally frank -- when you go another will take your place, possibly paying more each month, so they won't be losing out at all. Plus a finished IVA looks better on their books !
My opinions are merely that .. opinions based on experience. Always seek professional advice.
IVA Completed 23rd July 2013 .... C.C. 10th January 2014