If things haven't changed then they haven't changed - we have tried to ensure stability on that side.
The only time there has been a significant increase in expenditure was when we realised our first provider had not use the step change guidance as the iva was set up.
Our permissible expenditure was 25% less and finding that out helped us head off an increase in contributions because of a perceived increase in income.
IVA started March 2011, Completed March 2016 and certificate issued 11 days after final payment. It was not always easy but then some of the best decisions aren't.