My other car is a MINI!!!!
The issue you have here, as I see it, is that if the tuner does not know that the car is running dangerously, then they're never going to be prepared to rectify the issue free of charge.
It seems that they've been putting maps like these on cars for years, and because the fuelling is the same as standard, they're assuming it's OK.
Clearly it's not, but until you can get the tuner to accept there is an issue, you're buggered!
From the e-mail you posted above he clearly thinks it's fine, although he's clearly stuck in the last decade if he thinks a 4 bar FPR is required, and seriously, £99 for a 4 bar FPR? sounds a little extreme to me!