LCA1640AE Crankshaft position sensor located underneath the engine at the 6 o’clock position. You have an AJ26 (early V8) and this is the one you’ll need so the £200 sounds about right. The later AJ27 engines have a 2 pin sensor only and those are cheap and NOT interchangeable. I think I’ve only replaced 1 or 2 at most so I’d be suspect on just throwing a sensor at it. Did they get a code for the CPS? Maybe they should check for fuel pressure at the rail. Does it have enough fuel in the tank