I know, and I'm tempted to if this one didn't have such sentimental value. But £375 is still £375, and potentially £200 more than what actually needs doing to do it
Can’t they charge you something for investigation work, then call with a quote for the fix? Otherwise the £375 has got to be a maximum-possible-ballache figure (which you pay regardless of actual ballache).
The former is what garages, laptop repair places often do unless it’s a rush job.
You can buy one for a bit less than that.