Power sounder problem

[namalundu]

Put my 08 Vectra in for a service at my local vauxhall dealers and during the service it developed a power sounder fault. A new sounder was fitted and an adjustment to the boot and I was told all was well. After 15mins of getting it home the alarm sounded and kept on for a further three times. I took it back to the garage and they admitted that the original sounder must have been OK. On contacting Vauxhall Technical Branch they concluded that was either a break in the wiring somewhere or possibly a fault in the Body Control Unit. The cost for the wiring check approx £200 and the cost of a Body Control unit fitted approx £700. I don't really have a lot of confidence in their judgement so I asked them to disconnect the sounder whilst I consider my options. can anyone offer any suggestions as to the possible cause and remedy.

[Handyandy-UK]

Not an estate by any chance ?

[namalundu]

Not an estate. Also the boot light is off, wonder whether its wired in to the sounder circuit?