[Nognar]

Spent some time with the car today and can confirm the root cause of the problem is the battery.

Therefore I cannot personally recommend to anyone a Yuasa Silver battery.

More interestingly I tested it again this time with an Autel Battery tester (AL539B and recommended as I bought it specially for this as the cheap battery tester thought my battery was good) and it confirmed on the CCA test it needed to be replaced. It also confirmed that charging from the Alternator was all OK from the car. The readings I had originally on VAGCOM were down to the battery not the condition of the alternator, hence it was not taking a full charge.

Went to take it back to Halfords and to rub salt into the wound they refused to replace the battery as it tested fine on their machine. Battery had a 5 year warranty, was well within that and I had the receipt.

But hey there you go a lesson learnt.

I will write to Yuasa to see if there is any interest from them as its all in a little disappointing.