I have had a stairlift for 3 years now, from Handicare, who seemed to have an association with Age UK.
We have had a few engineer callouts due to a noisy mechanism
when the chair seat rotates at the top of the stairs. We took out an extended warranty, which runs until 2026, which included a yearly service. Due to the callouts, we do not appear to have received an annual service, although repairs have been done.
Their service is a bit tardy, but then they appear to cover a very large area.
All in all I have been pleased with my stairlift, and it cost in the region of £2000.00, IIRC.