Bad service from Hyundai Workshop

I took my car in to be fixed at Hyundai Meadowdale. They confirmed that the clutch had to be fixed. They quoted me and I paid for that service and also requested that they service my car as it was due for a major service. Upon collecting that car I could hear a sound coming from what I thought was the exhaust but the Workshop Manager says it’s sound like the petrol tank. When I told him that I never heard this sound before therefore so I will not pay for it to be fixed, he told me that his guys worked the front of the car not the back. I’m a girl that does understand technical car things and I think he is taking me for a ride. I took the car back on Wednesday so they can check the fuel tank issue but they did not even update me on the process 4 days later.