Hello Shakey,
I have seen this in the past and it can be fraud if your PPI money has not gone to your estate, also if your IVA was paid off in full (100p in £) then any left over will be yours, so it is worth finding out.
You can do this yourself by asking for the completion cert with the final financial breakdown and you can see where the monies have gone.
Or there is now a legal practice taking on cases like this ***Link removed by moderator - no advertising allowed**** I am aware you are not alone.
If you do it your self and find wrong doing then you can complain to the insolvency service who will look into this.
https://www.gov.uk/complain-about-insol ... actitioner
Hope above helps and get back what is yours