They were doing the same to me, until my internet actually began to act up. Turns out an animal had partially chewed through the wire going to my house. Also they upgraded my speed but my modem was too old to handle it, so I got a new one during their visit to fix the wire.

You should at least hear them out as to what type of problem it is. Like the other person said, it could be that they know about something that will be an issue in future.

Mine was working fine and they came out and replaced the line from the pole. Apparently those lines degrade and your speed suffers. You may not notice it until it’s an actual issue and then you’ll have to wait for them to fix it.