2001 Carrera convertible window regulator replacements

[DRM1967]

I have a 2001 Carrera 911 Convertible. About 6 months ago, I had the passenger side window regulator replaced. Immediately, the car battery would not hold a charge, and within one week, resulted in me having to have a brand new alternator. Last week, I had the passenger side small rear windor regulator replaced, and now my convertible top won't go down, and I am being told that I need to replace the Control Unit. The first incident "may have been" a coincidence, but I am finding it hard to believe that a scenario like this, resulting in thousands of dollars ($7,000 total work if I agree to this last work), could happen twice in 6 months. The top never had a problem until the window regulator was replaced. This car is in perfect shape and has 130,000 original miles on it. PLEASE HELP !!!!!!