Hospital demanding affidavit for change in DOB on medical records

I needed a change in date of birth of a patient's medical records, and provided a self-declaration along with the patient's aadhar card, but the hospital refused to accept the self-declaration, and is instead demanding an affidavit for the same. We mentioned a wrong date of birth on the admission form, and asked the hospital to correct it on their medical records on submission of the self declaration and age-proof (Aadhar card).