A friend has been using a well-known garage chain in the UK for some work on her 93 Convertible. This is a 2009 model with 99,000 on the clock.

I'm no mechanic but usually know when someone's giving BS.

She was told a new clutch and gearbox was required and proceeded with the work. She was also told that a new timing belt and water pump was required but that this was a separate job on a very different part of the engine. Is there any reason why, in the course of these jobs that the cowling and central console around the gear stick would need to be removed? (It was loose after they looked at it and hasn't been replaced very well.... the gearstick knob fell off as soon as she got it back and they said wear and tear)

In the course of other things a pollen filter was replaced. If this is replaced incorrectly could it lead to leakage in to the cabin? Eg. Excessive water on the floor.
The air blowers stopped working at this point too.
They reported that the wet floor is not the filters but have put new air filter in?
Muck had built up in pool underneath blowers and now is cleaned. Another new pollen filter has been fitted as that had got wet with the water damage.
Then the car breaks down with error message ‘traction control failure, contact service’.

Is all of this just an old car or is it the result of bad workmanship and a cascade of failures where one could have led to the next?