Once you have paid 100p in the £ plus the IP costs the IVA will cease. Statutory interest normally only applies to windfalls and not increased payments but regardless you would not need to raise equity as you would have no more liability to the IVA.
Thanks for clarifying that for me. My Husband will be so close to paying off the full amount by next July so don't think they will be chasing him for any extra. Shame it's not the same for me though, I think mine will run into the extra year.