First symptom was Parliament TV turning up on the Choice T channel.  Could not tune in Choice TV then Prime TV disappeared. 

Finally used Reset and re-tuned.  During tuning it listed a number of channels not seen before, but Prime and Prime +2 were on the list.  However, once tuning was done Prime was not available; if selecting channels it would go 7, 8, 9, 11, 12.  No 10 was available.

Any clues please

After several attempts at re-tuning it has come right.  Although it was recognising Prime on the tuning list, it would not display it, weird.