IVA annual review

Hi all,
I'm in an IVA with Payplan. £16k worth of debt and in fifth year of IVA. It has been extended till NOV 2020 as it took them a year to arrange a creditors meeting.
I did an annual review last Feb and made arrangements to pay arrears that I had accrued whilst poorly. I have been paying this and the monthly amount since March as requested.
Jan this year I started to get bombarded with calls from Payplan saying I was in arrears and that my plan was about to fail. I had heard nothing since Feb last year agreeing to the arrears. I called them up and they claim not to know anything about the review and say I haven't done a budget for two years. Now my plan is in failure, they are threatening to extend the IVA even longer or make me bankrupt.
So firstly, can they do this? and secondly the amount I am paying into the plan doesn't seem to be being passed on. Last June I had paid £3300 in, only £70 went to the creditors (in total). I have been advised that I should be paying 28% of the debt back to creditors but so far only 2% has been paid in. Even with the remainder of the payments including the arrears this does not equate to 28%. Does this seem right? Is this why they want to extend it?
I went into this plan because I wanted to pay my creditors back every penny and agreed to the monthly amounts (before things went wrong financially) to pay Payplan/creditors 88% of the debt back (but only 28% is SUPPOSED to be going to the creditors).
Does this make sense to anyone? I'm not mathematically minded but should they be keeping all that money? it is thousands and thousands of pounds.