Hi Caroline
IVA's can only usually be extended if the proposal provides for this. Sometimes proposals will exercise a discretion on the part of the IP to extend in order to achieve the dividend pledged, and this is what seems to be happening in your case.
I don't think that you can blame your IP for continuing to try and get the creditors repaid - and there are obviously reasons for this such as your missed payments. Talk to your IP directly about this, to get a fuller explanation, and make sure that you understand the basis of any additional charges which are likely to be made for extended supervision.
Regards, Melanie Giles, Insolvency Practitioner for over 20 years.
For further details contact me at
http://www.melaniegiles.com and view my IVA blog at:
http://melaniegiles.blogs.iva.co.uk