DOCTOR'S INVOICE: I NEED MY CLIENT INFORMATION

Ugh, this is so frustrating! I just want to settle/pay/clear my medical bill online, but I can't seem to locate/find/track down check here my client ID. I've checked/looked/searched everywhere – my emails, appointment confirmations/documents/records, even my junk folder! It's like it's vanished into thin air. Is there a way to reset/retrieve/obta