Hired a digger two weeks ago

Hired a digger two weeks ago, nobody on hire desk over the weekend so took till Monday sort it out. Digger was bigger than the one I ordered so wouldn’t fit in entrance. Delivered 4 hours later. Digger returned on time, with no problem, but diesel deposit not paid back two weeks later. Have called the branch twice this week to be assured that they took a picture of the digger fuel gauge before it left site and after. Claim i didn't refill the diesel. Can someone help me to sort this out