It wasn’t very clear. However, as I understood that u sub leased the store from some Indian who actually was leasing from Gulf. If this is the case then, u r doomed. Actually, the branded gas company never let sublease. U should have read the original lease contract between the gas company and that Indian. Now, all u can do is either sue that Indian or get agreement with Gulf directly to renew your contract. U must have received some incentives from Gulf selling their gas. Now, tell them u will work with them without incentive for year. They eventually have to lease the store to someone at some point anyway.
Actually, Gulf can sue that Indian for violating their lease contract by subleasing. Talk to Gulf directly, they might help you.
Good luck, hope u get your store back, buddy.