Can I hold the insolvency company at fault and have the decision to extend my IVA cancelled?

The insolvency company I am using has not acted in my interests i believe. As i entered my last year of my IVA I was informed it had to be extended and the amount raised. I asked why was this not addressed 2 years ago, and it turns out it it was their fault for not checking my yearly submitted earnings, and this has caused it to be extended.