Well, Pattaya isn't known for excellent diving. It has other virtues. If you are really looking into a diving holliday, I would suggest taking a liveaboard on the similan islands (Richelieu rock!).
That doesn't mean that diving in Pattaya is all that bad, just be prepared that visibility is not that great and most of the corals are gone.
There are a couple interesting wrecks (I would recommend diving the khram wreck) and the dive spots around koh Rin are great for coral life.
I normally go diving for one or maximum two days when I'm on holliday in Pattaya. I tried the following dive shops: mermaids (closed atm), adventure divers (
https://pattayadivers.com) and jomtien dive center (
https://jomtiendivecenter.com/). All give a good & comparable service and I would rather make my decision with which dive center I go with based on the dive sites they will visit.