Did a clumsy mechanic cause our Corsa's windscreen to leak?

My wife's 2005 Corsa 1.2 developed a water leak into the passenger footwell. This was diagnosed by the local Vauxhall dealer as a faulty body control module housing, which they replaced. This has corrected the water leak on the passenger side. However, in carrying out the work, the dealer's mechanic managed to crack the windscreen. The dealer agreed, without admitting responsibility, to replace the windscreen free of charge. This was done by a fitter appointed by the dealer. Shortly after this, my wife noticed that the driver's footwell was wet after rain. We went back to the dealer who advised us that this was due to a faulty bulkhead seal and it would cost £300 to put right. I pointed out that it seemed to be too much of a coincidence that this happened so soon after work had been done on the passenger side. Possibly the mechanic or windscreen fitter could have inadvertently caused this to happen?

Asked on 4 May 2013 by MG, Evesham

Answered by Honest John
It might be a coincidence. Corsa C models have suffered from water ingress through the bulkhead because the brake master cylinder is bolted to a plate which is bonded to the bulkhead. Pressure causes this bonding to fail, allowing water into the car.
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