vampirequeen wrote:The voltages and alternator belt are OK. Any other ideas would be welcome.
What voltage are you reading when the engine is running and the battery light is on?
You could try getting it hooked up to a mk6 compatible scanner. It should have logged some codes if the voltage is going too high / low.
If the voltage is staying at around 14v when the engine is running and the battery light is still flickering then I suspect it will be a wiring issue, probably a short in the cable from the warning lamp to the alternator.