This is very much like the sort of behaviours that caused me to take my business from CFS over the road to Bonus half a dozen years ago when I did my CPL. Twice in a row the instructor in my case didn't even bother to turn up for my scheduled lesson, so after the second and I was sat around for half an hour, I told them where to go and walked. Bonus had their problems as well, and are now out of business, but their level of professionallism was always head and shoulders above anything I saw from Coulson's Flying Circus.
I've no idea how good or bad your flying is, or what their rental and currency rules are these days - certainly planning to only turn up for the start of your rental slot, given the amount of preparation needed for a flight is seldom under half an hour, is very poor practice and I can't entirely blame them for letting somebody else take the aircraft.
But ultimately, you're the customer, and if they want your business, at the very least you expect some reasonable flexibility and a great deal of good manners. I've heard good things of CFS over the last couple of years, but if they've reverted back to "the bad old days" then frankly yes, walk and do your PPLing and eventual CPL elsewhere. Billins and Azure are both fairly reasonable for private flying at Cranfield, but for CPL you're out of luck unfortunately.