Gillespie Fuels & Propane

I have to pay for my propane delivery before delivery. I did that for a 100 gallon delivery. They put 130 gallons in my tank and billed me for it a month later. I'm being told their pump sticks and oops we put an extra 30% in, and I am responsible to pay for fuel I did not order. I am not paying for a product I did not order and was given anyway.