Disabled iphone

My granddaughter managed to disable her iPhone 11. We downloaded iTunes and connected it But it wants to send a code to the iPhone and we can’t get to it we have all the security information we need such as how it was bought the account it’s on everything but nobody can tell us how else you can get the disable off of it. If there’s an Apple support number that we can give them credit card information etc. we can’t find one and darling one 800 my apple didn’t work any ideas how to get this phone fixed