I ended up going bankrupt. I spoke to my IP and said I needed another £200 a month to survive and he said it wasn't possible to put a variation forward and he recommended I went BR. I was scared to death at the time, but now I'm glad I did it.
Historically the role of the IP has been primarily act for creditors.
In pre-IVA days a main role of the IP was (and still is) to act as a trustee in bankruptcy, or in other words to secure your assets and sell them off for the benefit of your creditors.
In an IVA they wear two hats. The first one is to act as proposer/nominee for the IVA where they are acting principally for you to secure the IVA.
Once the IVA is in place the situation reverses and they put on the 'supervisors' hat, reverting to a more 'traditional' IP role. They are then acting mainly on behalf of the creditors to police the IVA, ensure you make the payments and stick by the IVA rules.
Clearly there are IP's who take a more balanced view and I think most of them post on this forum, so present company excepted as they say.
However if you bear in mind the basic structure and history, it does seem to account for a lot of the problems people see hereabouts.