AES/PHEAA Student Loan Complaint

AES/PHEAA Student loan department,

Non-federal student loan Dealing with my lender or servicer Need information about my balance/terms Maryland

I was contacted by American Education Services. They say I cosigned a loan but they cant give me information because my birthdate doesnt match their records and i would need to send proof of my birthdate. How does a cosigner get approved with an incorrect birthdate. I have never been contacted till now. The applicant said she has received no statements in over a year at the time $700.00 was paid and the statement said - balance. Now they want to put me as cosigner on the hook for $ - they claimed is owed after sending the applicant a statement with zero balance. If there was a $ - balance why wasnt I or the applicant contacted for payment. They asked me to send a copy of official proof of my birthdate before they will release information to me as cosigner. When the credit check was run for cosigner that should have been a red flag that the birthdates didnt match and denied.