3 music related companies come to mind that have been above & beyond in their after service.
Hercules. I had a stand that was a couple of years old & the plastic bits went sticky, so I emailed to ask if they knew how to remove the sticky residue. They asked for my details & sent me a new stand.
Roli. My Rise25 which was about 3 years old, developed a charging fault & wouldn’t charge over USB. I asked them if they knew how I could fix it or what it would cost. They sent me a returns label (paid for shipping) & fixed it free of charge.
Cambridge Audio. I got a pair of Melomania 1+ earbuds last Xmas. A couple of months ago they wouldn’t turn on & had no lights on them. I emailed them & they tried some diagnostic things over email, but still wouldn’t work. They sent me a returns email & it was collected that morning & the new pair arrived the following morning.
I’d happily buy from these companies again.