I don't know if this qualifies. It would certainly be considered an old bit of kit now, but at the time it wasn't.

This will surely date me, but back in the day (mid 1980s?) I had paid to upgrade to WordStar 5.5 about three weeks previously. There was some minor technical glitch, I don't recall what, so in desperation I called their technical support and was told that WordStar 6.0 was now available, and that they would no longer support prior versions. I informed them that I had purchased every version of Wordstar since 2.0, and what I paid for 5.5 was absolutely the last nickel of mine they would ever see. (Probably the loss of my business was what caused them to go broke.)

I then called Lotus, they were happy to send me a feature-restricted demo copy of their word processor Ami Pro. When it arrived, it wouldn't install, and they were happy to spend half an hour on the phone with me working out the glitches. This was back in the happy days when you had to deal with IRQs and memory management, etc. I then bought the full working copy of Ami Pro, and would be using it still if it had ever been ported over to 32-bit platforms. For what I do with word processing it was hugely superior to Microbloatsoft Word. The point of this rambling narrative is that any company that would give technical support for a free demo download gets my vote for good service.

tanstaafl.