I can only speak from my own experience, but my IVA failed as I couldn't afford the repayments, which I agreed to as I was so desperate to get my situation sorted out. I couldn't 'shut up and pay up' as I didn't have enough money to live off - there was an error in the figures meaning I had £100 less per month that I should have had. And before you ask, yes, I did check the figures, and so did my partner, but we both missed it! I was left in a situation where my partner was supporting me, and I knew that I couldn't carry on like that for 5 years which is why I opted for bankruptcy, which with hindsight I should have done in the first place.
Regarding the IP question, yes, it does appear that there are some dodgy IP's and companies around. The amount of people on this site who's I & E is adjusted unrealistically to make sure that the IVA is accepted is scary.
Yesterday is history, tomorrow is a mystery, today is the present - a gift to make the most of.
View my blog at
http://skippy13.blogs.iva.co.uk/