Payplan used to be up there, among the faster firms. But, since they reorganised internally and then were hit by Covid before that change had bedded in, they do seem to have slowed down lately ! Not what you want to hear, but, as you say, while the IVA is on your credit reference files, your credit worthiness is pretty much dead in the water anyway.
Pay rises --- or parting with a chunk of them --- can be disheartening, but you are 'banking' these for that day when they will be all yours !
My opinions are merely that .. opinions based on experience. Always seek professional advice.
IVA Completed 23rd July 2013 .... C.C. 10th January 2014