Alternator nightmare

[Motorhomemadness]

Almost 2 weeks ago my motorhomes alternator stopped working suddenly. a strong smell of burning and a plastic burning smell.

Took it in and the garage said its died so it was booked in for yesterday, they fitted a 150 amp type, all seemed fine and the battery light came on in the garage, they looked and said its fine. told me the battery is low so needs to be charged while driving. The battery came up to 14.3 volts yet the battery light remains on.

The motorhome's battery monitoring system shows 50 amps coming from the alternator so its pumping out power. when the engine is on but not moving the battery light doesn't come on, only comes on while driving after about 5 minutes and remains on. Yet the starter battery is showing 13.8 volts.

Its now booked in to auto sparks in Carlisle on the 9th.

Engine is a 2.2 mk7, engine starts fine, the lights don't dim and the battery doesn't seem to be dropping.

I can't see it being the alternator as it seems to be pumping out good amps and volts. any ideas?