Friday afternoon, still no broadband so onto the telephone I went. What a pleasant surprise to get a UK call centre, with an incredibly helpful person who kept on waiting at the end of the line as we switched the router from one room to another and reported the changes in coloured lights, described sockets etc. Finally it was working and without an engineer's visit ! A big thank you to Ruth who was on the end of the line and to BT who will be refunding me £155 for switching which will more than pay for terminating the contract with TalkTalk !
Even better, so far the internet connection is faster and less intermittent than it was with TalkTalk, so it looks like this change will be a win and at least in the first year will be a cheaper service !