Hi, I suspect they may be victims of their own success to some degree. I've also had an (unresolved) grump with Krisflyer. In short I know I made Elite Gold by my renewal date this year, in fact I did so on that very day. However I have been left as Elite Silver and despite my emails asking for either an explanation or correction I still haven't had either. My wife has gone from Elite Silver to PPS (skipping gold altogether, but then she did one out and back to SYD from London without me).
I'm sure I echo the thoughts and feelings of many on here when I say how dissapointed I am with these loyalty programs, using the miles is a pain and often complex or difficult, in fairness I think (ie my opinion not a fact) that BA's is one of the easiest to actually 'use' in terms of spending the miles you earn. But in SIA's case I would be tempted to say that given the choice, I'd rather put up with a 'not so good loyalty program' and the keep the excellent service, planes leaving like clockwork, smiling, friendly and attentive cabin crew etc. Of course it would be nice to have both!
If people are tempted to vote with their feet because of poor service from a loyalty program or an inability to use their 'free' flights when it suits them, then I think it's a tiny bit misguided, fair enough if airline/overall service is poor then go elsewhere but when you are paying the fares, surley it's based on your choice of airline, not just based on the one that gives you the most free flights?