It really does depend upon what you and your creditors agreed to at the time of this variation. If you did not agree to this term, then the IP has acted inappropriately by accepting it on your behalf, but at the end of the day your creditors probably have been made aware that you have accepted the term, and therefore this could bring about the failure of your IVAs.
A face to face meeting with your IP personally would be a good start for both sides trying to understand where the other is coming from.
