Thank you.
I think finally Vodafone are trying their best.
The responses from TalkTalk have proven to be less than honest and certainly not at all helpful.
They are quite oblivious to how many regulations they flought.
To date the ombudsmen have been less of a watchdog and act as an retention of the TalkTalk i ineffectual complaints mechanism. There seems to be a total lack of accountability. I think they have got away with things for year and think there is nothing anyone can do about it.
Very annoyed by the public face of OFCOM and lack of any accountability. They may do something if enough people complain.

Just to give you the end of this story.

Vodafone never did get it. They ended up falsifying their own records and threatening their staff with disciplinary action if they did anything to help me. Said the problem was only with the three numbers I had given them even though I found others by the simple expedient of checking my contacts for those with TalkTalk email addresses asking if they were still with TalkTalk phone, then asking if they could reach me by phone. Unsurprisingly they couldn't.

Given this, I took the only option left to me I and moved to BT. After a process of over 6 months where TalkTalk repeatedly denied there was a problem, then repeatedly claimed they had fixed it when they hadn't, until it was finally fixed.

I have no idea if this was the only time that this happened ever, but by what I learnt on the way I have heard of other cases of unexplained similar faults. However, only a complete geek would have pursued it through to its resolution. It is too easy for a company to repeatedly deny there is a problem and refuse the customer any access to an expert who is capable of explaining what has gone wrong and why it is too difficult to fix. I almost gave up with BT until I realised taking a new number would leave it there waiting to be reissued to a new unexpecting customer with the same unresolved problem. I see why landlines are coming to the end of their lives.

Did you ever ask one of your TalkTalk contacts to raise a fault saying they couldn't reach your number using their TalkTalk line (but if they used their mobile or another line they goy through no problem)?

Two of the three original numbers identified were not appropriate to ask. Not technical or recent death in the family. Also I would be reluctant to suggest anyone attempted to get any sense out of TalkTalk. However, my son did take it up through his mobile provider. He was thoroughly fed up with repeatedly being asked for timed calls an abortive tests when it was claimed to be fixed off. He did persist for some time, but we decided to give up when he was offered a new SIM as a solution.
I am not a telco engineer but a mathematician with wide and varied problem solving experience. I have worked in environments where people work together to solve problems even where there were potentially blame games.
What I have read up on the OFCOM site shows squabbling factions with no engineering vision. If you do not recognise and acknowledge problems you will never be able to create robust solutions. I found no way to bring the fault to the attention and only achieved the record for the most tested local loop.
I think I was exceptionally lucky I didn't join the System X effort in 1977.