Brakes - certainly a big issue. Fuel pump and regulator - doubtful they would have picked this up - did you notice any performance issues when you purchased it?
Having worked in a garage, you'd be surprised how many components fail within a short period of time after having a tyre fitted, and obviously that is because the new tyre caused it!! It may be a co-incidence with those components.
Gearbox cable - again, it could just go (as mine did once in heavy traffic - lots of fun) with no warning.
It may well just be a series of unfortunate co-incidences (apart from the brakes of which there is no excuse) - this is probably why they have refused to take it back. It's very difficult in these situations as Carcraft have rectified the problems with no apparent issues.
You could pay to have the AA or RAC do one of their independent inspections on the car, and Carcraft would then have to rectify any further faults (apart from minor stuff like stone chips), but if the report comes up with nothing else, and then another component fails, it's just going to show that modern cars are generally rubbish and overly complicated with components not designed to last long in order for the manufacturers to screw you out of money