Complaining about child tax credits

Does anybody have any experience of complaining about child tax credits and the stages that you go through.
My child care payments stopped in April because I stopped working. I restarted working in June and I told them of the change or circumstances and I was told that payments would restart. But payments never started.
However the new assessment says that there are no qualifying child care costs.
I have tried many times to talk to the useless twats at HMRC and they simply say they don't know why I am not being paid. So they are really on the ball. Even my MP can't get any sense out of them.
To set the ball rolling I have appealed the 2010/11 assessment and the 2011/12 assessment. I have also lodged a formal complaint about the stopping of payments without notification and their refusal to discuss why they stopped the payments.
Now I don't expect any response having been dealing with these idiots since 2003.
Is the next course of action a mal-administration investigation by the Ombudsman or is there another stage of hoops that I have to jump through when HMRC simply do nothing and apply delying tactics.
I still have full child care costs and no child care tax credits. I also get no CM, David Cameron take note.

It might be easier to fill apply from scratch- that way they will back date it for 3 months.

I am not sure they will even do that. They simply refuse to discuss anything with me. They say it is with the Compliance office but I have a letter from the compliance office saying that they have completed their investigations and agree that I am owed child care but I disagree with the amount.
If they say that they calculate my child care at £86 per week why don't they pay it.
Two weeks ago I was on the phone argueing with them for 45 minutes. A complete waste of space.