Arcam rLink will not lock

I have a Arcam rLink connected via optical to my Panasonic Plasma TV. I have had it 1 year and it has been continually not locking unless I un-plug the power
cable and plug it in again. It worked fine for the first few months but now the
problem happens 90% of the time. Contacted Arcam and they insist it is my TV
however, it always locks then I use other DAC's? I'm stuck. Any suggestions.
Thanks