My corsa starts but wont rev and cuts straight back out?

Stalling when slowing is usually caused by a dirty or failed idle control valve.
Crank sensor faulty usually fails when hot, but if they have fitted a cheap copy sensor it wont work, has to be proper crank sensor from Vauxhall dealer spares department.
I think your garage is not very good,

tt
February 2011

my lad had a problem corsa one fault was as you describe.it turned out to be the coil pack shorting out.remove the two screws holding the pack on and check the condition of the rubber spark plug caps.his were perished.we temporarily wrapped a card tube around each cap and fitted it back on the engine,the fault cleared so we fitted a new pack.may not be your problem but is an easy check.

xs11
February 2011

would find another garage,air flow meters,egr valves,coil packs are common faults on these but it is no good guessing as it can cost a lot of money,would ask around and source a good,reliable person with the means to repair your fault.

cdc
February 2011