Number porting is something Ofcom care about a great deal, and it's led by the gaining provider - they are the ones you need to complain to.

In reply to a post by CRD32:

They said the only solution was to take.a temporary number for two weeks, then get the old number back.
This has happened and using 17070 I confirm I have the old number back.
HOWEVER on testing with my son on the iD mobile the problem remains. Will test again in a few days, but I am not hopeful.

So did the issue still happen on the temporary number?

OFCOM may care about it a great deal, but they will do nothing about it on an individual case.
You can report a number porting issue specifically and they will give you a reference. I believe they do some form of investigation, but you as a customer are not given any feedback
The reference can expedite (supposedly) the response under some circumstances, but I am unsure of it is any help here and no provider has shown any interest when I have offered it up
There is yet another group OTA? that has some responsibility for number porting issues, but I cannot see how a customer has any way of raising an issue.

TalkTalk, Post Office, iD (Carphone Warehouse)

I believe Post Office use TalkTalk.

Some doubt about how iD is supported

When with temporary number we could be reached by our son on iD, but never before (since 20 February) and now not again.

Fine on temporary number with my son on the iD mobile. I am using him as my tester.

OTA is a direction body, i.e. not a help individuals body

Thank you. There was a letter on the OFCOM site to the OTA that could be read in a different way. They do supposedly investigate porting issues and give a reference number. I did get one, but no feedback to the user.
I discovered the OTA website again, I think it was had a revamp and is now OTA2.
There seems to be a lot of direction from OFCOM (and money spent on PR and websites), but little or no practical testing or using examples as test cases to flush out problems.
I do not think there is any body that helps individuals.

Latest from Vodafone

The reason given to me is (as far as I can understand it is)

TalkTalk have seized the number and so preventing subscribers to their network calling me
The Openreach engineer is going to do something at the cabinet on Monday then come to the house
Vodafone will call on Wednesday to check it has worked
I was unable to speak with anyone who can convince me this is going to work, but at least is action of sorts.

Thanks for all your help, not convinced this will work, but I am at the mercy of my supplier. I will ensure the Openreach engineer explains it to me as far as possible and allows me to request a call back from one of the problem numbers.

Wish me luck

Openreach engineer arrived checked line, no problem with line. Switched equipment Vodafone to Vodafone at local exchange/MDF no change. Talked to Openreach Porting. Some anomaly but no difference in calls from one of my test cases. Escalation within Openreach.

Before you give up, I would suggest writing to your current provider, summarising the history of the problem and asking them to now take effective action within 30 days to correct it, failing which you will escalate through their Ombudsman procedure. The Ombudsman procedure is a bit of a bore for the provider, but it does at least get the provider to account for their actions which sometimes gets things fixed. If you go this route make a claim for all your time that has been expended on this and the inconvenience of callers not being able to contact you. Start with a claim for several hundred pounds, not that you'll be awarded much in practice.

From the history you describe, Talk Talk are likely to be the problem and it is notoriously difficult for one provider to sort out issues with another one. The tendency is therefore not to bother.

Forget about Ofcom and OTA- Government has decided that they should not deal with customer problems.

You could, of course, write to your MP saying that the Gov't regulatory process does not work and please would she/he fix it- occasionally this prods action, but these days only occasionally.