It turns out my last TalkTalk contact was hospitalised so I've got a new one.
Had a long chat with him tonight and he's sending out a new router which after some discussion we agreed was pointless - oh well.
He said he would get Openreach to do a lift and shift but the engineer would come to my house first - I thought the engineer went to the cabinet.
He said he would discuss with his colleagues, a pair change.
Progress I suppose.