Not sure which phone number Helly has given, but the Complaints and Enforcement telephone number is: 0845 601 4772. (It's the number I give to parents if they want to complain about me, and I have checked it on the website in case I got it wrong, but it confirms my telephone number ... sorry Helly, not trying to tread on toes here!!)
Unfortunately, unless you involve Social Services or the police, it is unlikely that OFSTED will be able to do much more than a "don't do this, (if you did do it)" type of thing.
I speak from very bitter experience (not my own!!!) as I know a minder who has had so many complaints made against her that it defies belief that she wasn't struck off. Unless you can prove wrongdoing, you can whistle for justice. Some of the allegations made against this minder were made by a child I minded, who told me what happened, and didn't want to tell his parents (it was a "secret"). He allowed me to tell his parents. I knew that they were one family in a long line of complainers.
OFSTED were requested to attend various childcare groups (because they'd be able to catch her out being wildly over her numbers - a very minor offence compared to the rest of them), were requested to be at the school (where they could witness the number of children in her car, and none of them had seatbelts), and to take on board that if so many unrelated families were making complaints over such a long period of time, maybe there was something in it. Guess what OFSTED said ... "we'll have a word with her ... again."
And no, she wasn't obliged to give up her registration. I have very little faith in their system. Sorry, another little rant over. Have had a jolly hard training session this evening learning all about OFSTED's new super-duper ideas for improving the way us childminders operate, and am not a happy bunny. Am going to have to start my own thread when I've calmed down!!