I am trying to register online so I can see my claims. Having trouble.

It says that my member number can't be found. There are three letters, a set of numbers and a letter at the end.

I need to be able to sign up because I have misplaced a bill and need to view my claims so I can pay this bill. I can't quite remember to which doctor's office I went to for this bill so that's why this is so important.

The bill is a small amount and I don't want to go to collections over such a small amount, because I couldn't find the bill.