I'm still learning how to properly run a campaign...
Welcome to this side of the GM Screen!
I told a player they couldn't "see" as a bat because they had been deafened ... and they spent an hour arguing with me
This is where you have to put your foot down. Give the players a bit of time to argue their case (personally, I give them 60 seconds) but then make the ruling and move on. If they continue the argument then give them the hard choice: either accept the ruling and keep playing or you pack up your stuff and no-one plays any more this session. Be prepared to actually pack up and leave. You should only have to do that once.
This player insists that their character is good even though they do this...
It doesn't matter what the player says; alignment is determined by the character's actions.
This cleric now has a reputation as a rude, shady character. Merchants will charge them higher prices, if they even sell at all. Anyone negotiating is going to ask for money up front. Anyone the cleric asks favours from is going to refuse.
Make sure that in-game actions have in-game consequences.
...their ACs have been around 22-25 since the beginning of the campaign (level 3).
First, as suggested elsewhere on this thread, get someone to check the maths.
Second, there are many ways of attacking characters that don't involve attack rolls; namely saving throws and ability checks. High AC doesn't stop an opponent from grappling or knocking prone, or from casting a charm spell.
Don't overdo it. If the players have chosen high armour then they want their characters to shine in combat. Make sure you are a champion of the characters, giving them chances to feel badass as the blows of their enemies bounce harmlessly off their armour.
The most effective way to deal with high AC is, however, the escort quest *evil laugh*. It doesn't matter if Brom the Barbarian has 22 AC if the princess he is escorting has 10.
As a GM, you absolutely have the same right to fun as everyone else at the table. You are not there to sacrifice your fun for theirs. If it is not fun then stop and have the difficult conversation with them, "Look, friends, this is not fun for me."
Finally, remember that stopping playing D&D with your friends does not mean they have to stop being your friends!