Oops, after posting I see you knew about the bus, sorry!
No worries - I do know about the bus, I regularly get the 5 or 5X between Bangor, there isn't much difference between the distances between LLJ and Llanfair and and Bangor and Llanfair but in reality the bus between Llanfair and LLJ takes longer because of having to go the wrong way along the dual carriageway out of Dwygyfylchi then turn at the roundabout to go to Conwy.
I do know the taxi office too.
All these options are great in an emergency (eg if a train breaks down, tree on line etc), I have solved the problem in this instance, my gripe remains that Arriva know about this timetable change (well at least some people there do!) but despite the fuss on here and on Twitter it's still not listed as a planned service disruption! That is all that I see as necessary in this case - advance customer notification of a planned timetable change, I am still failing to see why this has been so hard to do!
I mean there are notifications about other services, especially late night ones, where even if there are no replacement buses this is stated and people advised to get the next train (usually 10 or 20 minutes later, not 1.5 hours...)
