We have done many of these Tamko warranty claims and will be able to help you through the process. There isn't much that can be done to "repair" the issue if the underlayment is melting. The roof will need to be replaced. We will document the issue to submit to Tamko. At that point Tamko will have to approve the warranty claim.
We have a page with more information on this issue.
TAMKO(R) Warranty Inspections - The Roof Guys