Your IVA payments should have been calculated to be affordable. Are you living within the limits of agreed expenses? It is possible, but not easy, to get payments reduced, but they will only allow approved amounts for your household expenditure. Something must be adrift somewhere -- either they have not allowed a reasonable amount for expenses, have your income calculated incorrectly or you are overspending.
My opinions are merely that .. opinions based on experience. Always seek professional advice.
IVA Completed 23rd July 2013 .... C.C. 10th January 2014 http://foggy.blogs.iva.co.uk
You need to speak to your provider and show proof why you need to have your payments lowered.
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