2010 Skoda Superb electrical fault

Hi

I have a 2010 Skoda estate 2.0 auto. It developed a fault a year ago where the battery was draining overnight and after visits to 2 separate garages (costing £900), it was diagnosed as having a faulty drivers seat module/actuator. I finally found one and it was installed yesterday. Unfortunately, the power drain started straight away so its obvious the module was not at fault.

When the seat power wasn't connected, there was no power drain.

The garage, who are vw/audi/skoda speacialists say that it may require a further 8 hours of investigation costing another £640.

What could be causing the power drain? I am close to just selling the car for next to nothing as it is becoming a drain on my finances (excuse the pun)

Thanks for any advice