contact your local children's information service, you can get their details from www.childcarelink,gov.uk. Or try ofsted again - name and address should be enough for them to investigate and you may get someone more helpful next time!
If you're a local councillor, surely you can speak to the Early Years team at your council offices? In this borough, at least, I used to get a call from the council every 6 months or so, to see if I still wanted to be on the CM list for prospective parents. They must have some knowledge of the CM's in your area?
Go on to the NCMA website ( assume you are in England not Wales, NI, Scotland ?) and find the details for your local development officer - she will know exactly who is who.
Other than that, can you not call in as a prospective parent and ask to see her certificate of Registration which we are all legally obliged to display prominently?
A CM can legally look after one child under 1, a total of 3 under 5s, the rest 5-8 and over 8 as many as insurance would allow but only if not affecting care of younger children, so it is not unheard of for a CM to have upto 10 I suppose, although I personally do not agree with that.
They may look after more or two babies etc with a variation but a new minder wouldn't get this anyway I doubt, unless it was twins.
How to Complain - guide from Ofsted. If having called Ofsted you feel they are not going to do much... then I suggest writing, marking the envelope for the attention of the Enforcement Team. Include as much detail as you can - including a copy of that leaflet you mention if possible.
As you are a councillor and someone owes you a favour in the Early Years team, have a chat with Early Years telling them the name and address of the person, to see if they can search on iChIS (most councils use this database system), to see if the person exists as being registered.