cliffcoggin

It's likely there is an airlock as a result of the work on the cooling system. A vacuum applied to the reservoir should clear it.

The Yuasa 9000 series are 12 volts so Rob must have a standard starter motor, not the starter/alternator of hybrid cars.

CVTs have what are effectively an infinite number of gears between minimum and maximum, hence the name Continuously Variable. It is misleading of Audi and others to falsely claim their boxes to be CVT when they have only a fixed number of gears, 7 in your case. Look up the gearboxes fitted to DAF vehicles many years ago for an example of a true CVT. They were dreadful things.

That new information means all bets are off regarding diagnosis. Mapping has a bad reputation for causing engine problems. You are right about the symptoms of a slipping clutch, (engine speed rising with no change in road speed,) so we can rule that out. I still believe it is an engine problem, though it needs somebody more knowledgeable than me for a diagnosis. By the way your gearbox is not CVT.

This topic is going nowhere so I am closing it.

My guess is the injectors or fuel pumps, but because their repair will be expensive it would be well to get confirmation from an electronic diagnosis before buying anything.

What engine and what fuel Declan?

In the end John beggars can't be choosers. If the Spareto part is all that is available I would take a chance on it or go with Gareth's suggestion of a longer bolt with a nut. As long as you get the right clamping force between the two components you will meet the designed strength requirements.

Has your paid subscription to Audi lapsed?

It's not the starter motor Rob. That much I am sure of so don't waste any money buying new parts until you have a confident diagnosis. If the battery is in good shape, and I am not convinced it is, you need an electronic diagnosis.

Radio and GPS aerials used to be entirely separate items on different cables, but maybe technology has moved on since then. Is it a shark fin aerial on the roof? I have read they can become loose.

You will be very lucky to find a lens of any brand. Have you tried online car breakers?

I would not trust any work done by the clowns at Halfords which is why I suggested a professional test, but if you choose to believe them the next step is to take the car to a garage, either Audi main dealer or specialist independent, and have it diagnosed on a code reader.

If radio is the only fault my first suspect would be the aerial connection.

Please let us know the outcome.