Well, I've only left one club. What drove me away, was constantly turning up to go flying only to find out the aircraft was grounded for some reason, or someone else had flown it away and got stuck there with weather.
I wouldn't have had a problem with either issue, if I'd simply got a phone call advising of this, to save me the bother of planning my day around flying (and that of some excited friend coming for their first flight).
So, if there's a problem, just call your customer as soon as you know, and let them in on the picture.
I know it's obvious, but if it was done at this school, I'd still be paying them my money.
dp