immobiliser help

[Tallywhacker]

Hi everyone..member for a couple of years now but first time poster.

Sorry for my first post to be a problem but would appreciate any/all help

I have a Vectra C 2.2DTi 2003 model, anyway cars has been running fine for the 5 yrs I have had it until last month....my car had been sat in my works unit for 3 weeks....until some t*t I work with decided one night to put my stereo on to listen to while they were on call in the depot one night(they flattened the battery) anyway put the key in and it just came up with padlock and car symbol on display....went and got spare key from home same thing.

Got an independant Vauxhall garage out to recode key with tech2 they turned up and put a 12v booster pack on to find it wont read the ecu?
They recovered it to their unit 2 weeks ago then phoned me to tell me it was main fuse board ecu(?) and someone must've put 24 volts through it and said it would be £650 to fit new one....sod that and I bought a de-paired 2nd hand one from online. They fitted that and then tell me all the modules have gone now and theres no power to anything.
Everything electrical was working fine on car apart from not turning over and above symbol on display. All fuses working and in right places/right fuses etc

They have now sent it to a Vauxhall dealer(Brandish's) to diagnose, but yet the dealer wont talk to me even tho its my car.

All they have told me is that it needs a new CIM module and control unit as someone has overvolted it, but they cannot gaurantee it will work and that i might need an ECU and told me to discuss it with who i gave the car to.

I am now looking at a bill of £800+ and no-one can tell me what the problem is or why it happened and in the meantime I am carless and up the proverbal creek without a paddle.

I've spent forever and a day scouring this site and others with no real definate fix or cause. Would appreciate peoples help or input if anyone can as I now go off to find an aspirin the size of a dutbin lid for this humungous headache.

Chers Tally