1998 Vauxhall Corsa cant use my car for more than 5 mins?

Engine Mechanical problem
1998 Vauxhall Corsa 4 cyl Two Wheel Drive Manual 80.000 miles

hi im going crazy with a serius problem with my car.I have a corsa 1.6 16v sport r reg 1998. My timing belt snaped on the moter way. So I had the head referbed  £660, he rang to say done pick up, wen I got near home about 16 miles away the car staled restarted but with a slight missfire, ever since its been getting alot worse. Now thers blueish smoke from the exhoust alot. With mega loads of black sut in the tail pipe, also the plugs r getting full of black sut very quickly after about 2 go, s of 5 min run, the car only runs for bout 5 mins then stalles at lights will restart but I have to rev or it will stall again there is a very bad missfire after the 5 mins at lo throtle and the car sounds like a tank loss ov about 30% power too, ive changed map sensor thermostat sensor new plugs new ht leads its fine for the first 5 mins then prety much undriveable. I had a conpreshion test dun he said it wer fine but I wernt there wen he did it? Please please help ive only just bought the car had it 10 mins wen the belt snaped. And we have no money for a new 1, thankyou, barry