Cannot get into account for 1 week now

I can no longer get into my email account: ***@***

I have been locked out since at least 11/11.The verification process does not work. Once I get a the verify code sent to my phone number or alternate email, I punch it in, but then am taken back to logging into one of my other yahoo accounts, but NOT ***@***. This has been going on for a week. I've been going to Yahoo Help Central sites incessantly for a week and have been able to resolve. I followed all instructions, cleared cookies, caches on all devices (desktop, mobile and tablet), nothing has worked. Sometimes my mail acct is not recognized.
I am the rightful owner of this account. When I send a test email to ***@*** from another email, I get the following bounced message: <***@***>:
Remote host said:
554 delivery error: dd This user doesn't have a yahoo.com account (***@***) [-5] - mta1168.mail.gq1.yahoo.com
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