iMessages getting sent to my old phone number

I changed my phone number and my messages are getting sent to my OLD NUMBER. I was told I need to upgrade my 8 to new phone. Bought a 16. Issue persists. Called numerous times to att and apple. I have toggled numerous settings, even got a new Apple ID. As long as I am sending I messages they continue to go to old phone number. Yes I have deleted my contacts and erased all traces of the old number on the new phone and Apple ID account. Still not working, huge privacy and security issues.