Transit Visa for a 2.5 hrs layover at Kunming then to Lhasa

We are a group of 32 travelling by China Eastern. We will depart from Kolkata for Kunming ,and after a 2.5 hrs layover at Kunming , we will take a flight by the same airline to Lhasa. Do we need a Transit G? The airlines says we need and when we submitted all our papers the Embassy says we need only the Tibetan Permit. Please clarify as soon as possible as we have only 2 weeks left to departure. Thank You.