Normally the IP can only sanction a reduction of up to 15% without having to ask the creditors for permission.
It's not really unfair, I am afraid it's business. The creditors loaned you the money and want to see as much as possible back. I would imagine, even after 6 years they will be wrting off a fair chunk ( even without all the interest you are saving in the meantime ), so you will still be ahead of the game at the end ... and debt free
As an example .. I owed one CC company nearly £13,000 and was just paying the interest each month. Assuming I wasn't in an IVA, after 5 years I would have paid that company over £12,000 and STILL owe them the £13,000 !!!!! In the IVA they are getting about £4000. So I have "saved myself £21,000 !!! And that's just one creditor!
First time I have actually worked that out -- puts things in perspective !!!!
My opinions are merely that .. opinions based on experience. Always seek professional advice.
IVA Completed 23rd July 2013 .... C.C. 10th January 2014