I just through I'd update this one for people now it's resolved.....
TPE said when they saw the ticket "but thats a Northern ticket..." I said that was issued by the onboard TPE guard/train manager
"Oh, we shouldnt have issued that ticket that was wrong of us. Here have a full refund." Despite offering them the monies for the correct TPE fare less half the agreed Delay Repay they were said that the train was cancelled had been very inconvenienced, so sorry, deep apologies, so they were happy to refund the lot, especially since it was a wrongly issued ticket...
Northern were basically a complete faff. They first insisted that the ticket was presented at the point of sale for a refund - I asked how refunds work at a TVM then... it went quiet. Much poking and prodding led to a request that I post the ticket, so I did then they said they hadn't got it - so I posted the pictures of the ticket and the envelope it went it. The argument then was that the buses were running - so I pointed out there was no announcement no notices and if they sell a train ticket and then replace with buses thats sufficient grounds to abandon journey as they never said at the point of sale....
Went quiet again....
Posted a letter before action in the end...
Refund cheque for the full amount arrived three days later.
I am not impressed with Northern at all. TPE despite screwing up on the issuance of the ticket have been more than reasonable.