A friendly Openreach engineer turned up today, noted that my In Laws were the first to be on infinity in the cabinet, also said that 29mb was a bit over optimistic for the distance from the cabinet.
He put his tester on and saw packet loss, he said he would have to go up the pole to check it there but would have to call another engineer to be there with him, he asked for my number and said there was no point in me staying and he would update me later.
He called me a few hours later to say that, he had replaced the cable from the pole to the house but it was a rein problem and they had narrowed it down to 2 properties, this would be passed onto the rein team (2 members) and it could be a while before they could look at it. He also said that even if the rein team narrowed it down to a particular property they had no power to enter or if they found the source of the problem, to insist that it was replaced/powered down.
The engineer said that the best my in laws could hope for was 20meg download.
I still live in hope