Apple ID does not exist

iPad is saying Apple ID does not exist. I know it does because I set it up. I cannot log out of the Apple ID as it’s completely grayed out. I’ve tried contacting Apple support and can only do chat. It’s been very unhelpful. The reps think I’m stupid and try to walk me thru the same steps I’ve already done. To top it off, no one believes that the Apple ID is grayed out. Someone was supposed to call but never did. I tried doing a reset but it requires the Apple ID and password. Since it doesn’t exist per Apple, I get no where. It’s an iPad 7th generation with cellular. Even the list doesn’t have this iPad as an option.