EXCLUSIVE

10:30 AM PT -- We checked and the Pizza Hut Abby called does not offer the $5 flavor menu -- it's a national deal, but individual stores don't have to honor it.

Abby Lee Miller treated a Pizza Hut manager like a pre-teen girl in a tutu -- unleashing her social media soldiers on the guy after an argument over her order.

The "Dance Moms" instructor went ballistic Thursday night when she called a PH in Santa Monica to place an order. Our well placed pizza sources tell us Abby was put on hold, like anyone else might be.

When a PH employee got on the line, we're told she inquired about the "$5 pizza deal" ... but when the employee didn't know what that was, Abby got pissed and asked for a manager.

We're told the convo got heated. Abby claims PH hung up on her, and then she hit the nuclear button -- posting the store's phone # to her 2 million Instagram followers, asking them to call "the idiot who keeps hanging up on paying customers."

Our sources say the store was flooded with calls until closing, and it was so bad they had to stop answering the phones. We're told PH has been reaching out to Abby, asking her to take down the post as they're concerned it will continue to screw up business, but she hasn't responded.