It's not that simple, modern Fords have what is known as a "Smart charge" system, in essence it's computer controlled.

Anyway it sounds like it's not charging correctly, therefore I would first off all verify this.

I thought the MK2 was hydraulic assistance, but it sounds like it's electric?

If so this would explain why that is not working.

It should go back to the garage, as sending it away with warning lights, clearly is not fine to start with, I don't see why they replaced the battery either!

Martin