Stumpy 2, sorry to here of your problems. I have a pc from mesh a year ago and like you it has various issues. It kept crashing and the first time it happend was within minutes of first switch on. like you I kept loyal to them and then went over the 28 days. They then played hardball and wouldnt refund. Did my reserch and as it 'wasnt fit for purpose' kept at them under trading standards law. Got my money back after 6 months, so it is worth keeping on at them, as clamly as possible. I started to put everything in writing and contacted trading standards in the end, who helpfully sent me some details of the approch to take.
Hoep this helps, good luck with it