I could see his point. After all, I'd already done the required pre-change backups, pulled up the right screen and selected the right option, and then as soon as he walked in the door I carried out the change and hit "reset system". He didn't actually have to do anything related directly for the change.
The thing is, though, it's a question of what he may have had to do. The basic change was to change the setting of a radio button. Trouble is, that throws up a dialog box saying: "If you go ahead with this change the database will be erased and must be restored". Now, 99 times out of 100 this is a simple process, but just every so often there's that odd chance that something doesn't quite play the game. Then it's rather handy to have the guy who does this stuff every day on hand to help out the guy (me) who does it once every few months.
And anyway, my service provider is a pretty laid-back entity and is more than happy to do other stuff while waiting for the various restores and changes to happen.
So I did the change, and he spent the time looking into two queries that I had regarding the operation of the system. Everything went fine, he was on hand in case it didn't, and we're all happy.
And I'll carry on with the maintenance contract for the time being, thanks.