So if they do deliver why would their staff tell us when it was 8:15 p.m. that they're not delivering any more pizzas tonight

You need to call earlier in the night and not almost when they are ready to go home.

According to the website they're open until 11 p.m. on Saturday. That's okay we ordered our pizzas from Domino's thanks for your answers though

They close at 9 every night. They probably cut off deliveries so the drivers can get back in before closing