Case Sensitive Vlookup

Hey yall,

I am having a problem where vlookup will pull the wrong account number because some are "123a" and others are "123A" and it will not differentiate. Any ideas? I don't know if vlookup can do this or not.

I attached an example where I know account number, phone, and contact. But it is pulling the wrong info over because it will not do an exact match. Any ideas? Thanks so much for the help!