filed taxes in 2/2021 for tax year 2020 for my deceased father.still have not received the refund due. contacted IRS 3 times .the last call the agent stated I did not have a form 1310 on file. I filed thru turbotax and it shows a 1310 was submitted.

[Mike9241]

these are the 3 options

A Surviving spouse requesting reissuance of a refund check received in the name of both the decedent and the surviving spouse. obviously not your situation
B Court-appointed or certified personal representative (defined below). Attach a court certificate showing your appointment, unless previously filed. did you check this box? form 1310 not required but you would need to paper file to attach the required documentation
C Person, other than A or B, claiming refund for the decedent’s estate. Also, complete Part II. this box?

what did the agent say to do? 

[fanfare]

did you mail in a copy of your letters testamentary and the death certificate.?

You have to mail that also if you e-File 1310.