cliffcoggin

It might be the caliper has seized, but I think it more likely there is something jammed against the disc, such as a broken fragment of pad, a stone, or a broken spring clip. If so, it should be easy to remove if you have any tools with you.

Jordan. Just to clarify the problem for me, are saying the pedal is really locked solid, immobile, and impossible to move no matter how much force is applied; or is it just very difficult to push down and lacking any servo assistance?

Is there an equaliser for the two cables Gareth? I have not worked on A3 handbrake so I am not sure. Equalisers were a common source of jamming back in the day.

The solution is simple: you need a new battery, however you and your father have convinced yourselves that the existing battery is fine, so I don't propose to argue any further.

Not enough information. Does the fascia illuminate? Can you select channels? Can you change FM to AM etc? Do the steering wheel buttons do anything? Fuse, radio code (password), aerial connection, power connection are possible faults but without a complete description of the problem we can only guess.

A battery that is fully or largely discharged can be damaged in such a way as to be able to still crank the engine over but not supply a stable enough voltage to the electronics, which can lead to the sort of problems you reported. I am not saying the battery is entirely responsible for those problems, but it is a strong contender. See what the code reader tells you before doing anything.

I agree you need the car scanned by a decent code reader, however the battery warning light may be a clue. A substandard battery can cause all the symptoms you describe and a few more that you have not. I assume the battery was disconnected during your repair work. Did it lose charge during that time?

Stuart. While it is possible the water is rain coming in through the heater if its drain hole is blocked, or the heater matrix is leaking engine coolant into the cabin, or the windscreen sealant has perished, the obvious candidate has got to be the rag top. The fabric may be intact, but it must have some sort of seal around the edge which may have been damaged. I have never dealt with a soft roof so I can not be any more specific. You also said cleaning the drainage channels helped, so if they are accessible can you test each one by pouring a little water through them to see if they really are clear?

YES. Even on my 2007 car.

New batteries have to be coded to the car to get full functionality of all the electrical systems. Was that done?

Glad to hear the solution was so simple.

That's a good start. Do let us know if it solves the problem.

The possibilities are almost endless. ABS system, ECM, faulty gear selector switch, defective battery, wrong wheel/tyre sizes for example. You should get the car diagnosed by a decent code reader.

What do you mean by "changing gear strangely"?

Harry. Smoke like you describe is an MOT failure. Assuming you bought it from a dealer take it back for a refund or repair. On the other hand if you bought it privately be prepared for possible high expense, and tell us about mileage and service history.

In addition to Gareth's question, what size is the engine and how many miles has it done?

I have no idea what that means, but presumably you know how to enter the search terms of your choice into your preferred search engine. In other words the answers you seek are at your fingertips, and you need no particular expertise from this forum.

Yes, very suspicious. Possibly the rack sensor or its wiring was damaged during the wheel bearing change. It would not be the first time that repair of one fault created another by disturbance of the wiring. Apart from going to another company for a diagnosis, (without mentioning the problems with Vasstech or Kwikfit to avoid any prejudice), I don't know what to suggest.

Tony. The link leads to ten Duck Duck Go search results, only the first of which is a Youtube video, the rest being articles or web pages. If you don't like DDG use the search engine of your choice. P.S. I use DDG as my preferred search engine because I will not touch anything made by Microsoft, Google, Apple or any of the other spyware companies.

Definitely don't rely on Kwikfit for anything except tyres. They know little and care less. You need somebody that can properly diagnose the problem. Your best option for that is an independent VAG specialist.

https://duckduckgo.com/?q=A3+wiring+diagrams&ia=web

Yes that may be the problem. Having bought new parts why not fit them and prove the point?

I said the design was clever, I did not say it was good. Nevertheless it lasted 13 years which is considerably longer than many of the more essential components of a motor car.

I wouldn't call it a flawed design, in fact I'd say it is rather clever, however no machine lasts for ever. Yours has lasted 13 years so if you use rear screen wash normally through the new motor it will likely outlast the rest of the car.

Most likely the clutch needs to be renewed. How many miles since it was last done? Does the shudder happen as the clutch is slipped, or when it is fully engaged?