Iphone X changed my passcode on its own

My iphone X changed its passcode on its own! I have had the same passcode for years now and it's a very simple passcode (think 1,2,3,4). Yesterday night I was using my phone and I put it down for a min, and when I picked it up again, Face ID didn't work and I had to put in my passcode. Guess what, my passcode was incorrect! The same simple basic passcode I have used for years was INCORRECT. Unbelievable! I had to make sure I have not lose my mind, so I asked my sisters who knew my passcode if it was the correct passcode and they confirmed it. So now my phone is disabled, and I have a 256gb phone with majority of its content backed up on iCloud. I cannot believe this, now I have to restore my phone, it is going to take weeks for all my content to be downloaded on my phone again. I contacted apple support and scheduled a call, but I didn't receive a call on the scheduled time. I cannot believe that we are paying so much for a device, only to be locked out of my own device for no reason whatsoever, and Apple is not offering any help. I have had it! Please help good samaritans!