My dad said at least he is being "courteous"?

I mean, it's annoying for sure. But if he's agreeing to what you ask and you don't have anything else in place, i'd suck it up so i could have the choir. But that's just me.

Thing is though I found another choir (thankfully). That incident leaves a bad taste in my mouth. Since nothing was set in stone (since I couldn't get ahold of him), I didn't even know if he do it or not.

He was not being courteous. Not in any way, shape for form. He was unprofessional for sure

I don't even want to call them back TBH.

I wouldn't. You already have someone else. If I called i'd probably tell him off lol

I can't cause its a community where everybody knows everyone, old family friends etc.

Ahh. I would just say thank you, but since I didn't hear from you in time I found someone else

That's not curteous at all. I would tell him that due to his lack of communication, you booked a diffrent choir. Then thank him

Courteous would be replying in a timely and professional manner. He was rude to reply that late!

Then I would just be polite, but firm. Respond to him via email if possible and say something like "unfortunately, since we didn't hear from you for 3 weeks, we booked another choir. thank you for your time".

Pointing out their mistake, but not going overboard into rude.