In PA, a property line dispute isn't covered under an owner policy, however, that may not be the case in GA.  As with any title claim, look on the policy jacket for the correct title company address for submitting a claim.  Send a copy of the policy and a letter explaining the dispute to that address via certified mail, return receipt requested.  Make sure you include your contact information.  You may also want to send a copy to the attorney who issued the policy, but the claim is made directly with the title company.