Rant about ONE manager consistently ruining my day.

I work in a store where I'm lucky enough to practically never have rude customers. Stupid ones? Yeah dozens upon dozens a day. But I've never had someone get angry, impatient, demanding, etc with me except for whenever one manager is the MOD that day. Every other manager is very understanding and, while may get irritated if it happens too much, doesn't mind helping a customer.

There's one though that straight up refuses to help whenever a customer calls asking if we got something in stock, leaving me with someone yelling at me and upset because they know it's bullshit when I tell them "sorry, we can't check that for you right now" or "we're out of stock" knowing damn well we never even looked. Acts like I've personally insulted him whenever I call for backup, a carry out, price check, etc. Literally the only days I ever have rude customers are with him as the one in charge because I'm not allowed to leave the register and customers are pretty much told "no, go find/do it yourself" to everything. It's infuriating and I don't blame the customer tbh because I'd be upset too if it happened to me!

I've brought it up to another manager before and just got told "well he's the freight flow supervisor, he has other things to do" like ??? Yeah, sure, but if he's the manager on duty, especially if he's the only one on the floor as well, he has to do other stuff as well. Not shirk your duties and just make people pissed at me for zero reason. Before I became a cashier, whenever I was on the floor and called for backup or to help with something I stopped whatever the hell I was doing (as long as it was safe) IMMEDIATELY to go assist. Why do you have to get this shitty attitude about it?