If you read thru the warranty, you'll see that problems due to contaminated fuel are not covered. Been there, done that.
Besides having a sample of the fuel analyzed, make sure that you save your receipt from the station. If you used a debit/credit card, where it shows up on a monthly statement, you're covered. That's legal proof you bought the fuel there.
Also, have whoever is doing the repairs fully document everything they find and have to do to restore the vehicle to running condition because of the contaminated fuel. If having other work done at the same time, make sure they break out the fuel related items separately.
Armed with the above - an analysis of the fuel, proof of purchase, and documentation of repairs - you shouldn't have any problem talking with the station owner and being reimbursed for the repairs.
Matter of fact, you should go ahead and contact the station owner NOW! Let him know what happened and that he needs to check his fuel to prevent other customers from having problems. This will actually save him money, not having to pay for repair bills for several other vehicles as well. If you're civil about it, and he's anywhere remotely decent, he'll appreciate the heads up and it'll be that much easier getting reimbursed for your vehicle.