Brakes and wheels burning smell

I had it motor and serviced end f April 15, I had rear brake discs/pads, cv joints and shock absorbers replaced, since this the car has made a terrible screeching noise after driving for about 15 minutes, sometimes it stops when I press the brakes! The rear passenger wheel is also very hot and smells like burning rubber if I drive for about 20 mins, then today I was approaching traffic lights with a car in front of me and my brakes failed altogether, my foot went completely to the floor and I had to lower the gears, pull my handbrake on and hit the curb to stop, the roadside assistance came out and said it was probably an air bubble and they needed bleeding which he did, but the brakes don't feel the same, I have to press the pedal down a lot further than I did, I had the car back in the garage who done the repairs on Monday just gone and he checked the wheels and brakes and said they were ok, he drove the car for about 10 minutes and heard no screech or smell, it doesn't do it all the time and it's not constant, I've noticed on really hot days it's worse and gets really loud, sometimes it sounds like a screech and sometimes it's like a jingle bell, my mechanic is taking it in tomorow but he's at a loss as he said he can't identify it if it's not happening when he's got the car, has anyone came across this problem before?
Thanks in advance
Lyndsey