Giving this guy the benefit of the doubt, how would the match play out with a line judge there? Do we still call our own balls and they overrule the calls, or do they make all the calls?
In the Eastern section, officials rove from court to court, usually staying for an even number of games. You're required to call all the balls aimed at your side of the net, giving your opponent the benefit of the doubt. An official will promptly issue a correction if a mistake has been made.
Any person on the court can call a service let, including the official.
Any player can request an official watch games from their match. After a point, the player excuses themselves, finds an official and asks for help. A loud, long, drawn out argument with your opponent about where a ball landed is not necessary. Even in a match that goes smoothly, it's common for players to request officials at the start of tiebreaks.
If a ball rolls from another court (no lets for balls on the court at the start of point) and you'd like to replay the point, you should make that call immediately. As an official, if I don't think the ball is interfering with play (it's rolling near the net or back curtain) I might not stop play, but sometimes, I will stop play if it's rolling towards a player's feet or otherwise in a position where it might interfere. It's a tough balance to strike sometimes, so if you want to replay for something, stop play immediately. If you don't and continue play in good faith, it will be harder to make your case after the point is lost. The rules prohibit players from having 2 chances to win a point. Similarly for hindrances.
Officials will call foot faults.
If your match is in progress, don't leave the court (as in for a bathroom break, or change of attire) without notifying the official, except of course, if you need to leave to notify the official because they're not on your court.