Shimano [now] recommend replacing the rear cable inner quite frequently. It's not as often as every 2,000 miles, however, which is in theory how far that one had been used for (since the Perth service). I've had rear cables begin to fail in the shifter (it's due to the very tight curve around the ratchet) after about 5-6,000 miles; twice. That's 'coincidentally' how far they've cycled since setting off. It might be surmised that the Perth service failed to replace the rear cable :-\ If so, Amy's may well fail too, in the next not very long. Given that they had a multi-hour delay after the Perth service for some gear/brake related reason, that was not the most successful of bike rejuvenations really. I hope the next one goes better!