Hi George,
I don't know if this helps or not.
I had a Fiesta recently that the customer kept getting flat batteries with. I found that after starting, the car gave a short charge cycle then switched off the alternator completely. The only way I could ensure it remained charging was to put the headlamps or other loads on. The car seems to have a crude energy recovery system on it, where the moment you lifted completely off the accelerator the alternator was powered up and charged the battery. A sort of primitive KER system. I road tested with a meter on the battery and you could feel the additional braking as the alternator came on line and the battery voltage rose to 14 or so volts. This of course has a LIN bus alternator on it.
I am wondering if your 208 has a similar system. Run it with some loads on and see if it charges then. Try a roadtest with a meter on it too. Perhaps your LIN bus error code has been generated when you disconnected the wire for it.
I think the manufacturers are up to anything they can do to achieve lowest CO2 figures for taxation purposes. How these cars will fare in the future with sulphated batteries I have no idea, as the only way to make this work is to always have the battery partially discharged.