I'm not an expert on this, but I have doubts about being unable to resolve this problem after a given date.
Who told you this? IRS? SSA? Other?
I previously suggested reviewing https://www.irs.gov/newsroom/a-name-change-affects-a-tax-return
Did you do that?
Have you filed Form SS-5 with the Social Security Administration? In person at an office or via mail?
If via mail, did you send it USPS registered mail, with a return receipt to ensure they received it?
Did you enclose the needed support documents?
https://www.ssa.gov/forms/ss-5.pdf
If not, I suggest you gather your forms and documentation and make an appointment at your local Social Security office to submit your paperwork. Alternately, you could make an appointment to have them check to see if your paperwork was received.
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