Petrol disappeared from Renault Clio

4th Dec I put petrol which my car was on 3/4 full and I needed to have it on full tank. When starting the car, we picked up the needle on gauge didn't move up and petrol attendant advised it should move up when we drive, after about 45 mins it moved but down and as we were driving it kept moving down.

Contacted the garage regarding this whole situation and met up with the owner on Sunday who showed me the footage and their records that the petrol was indeed dispensed into the car as we believed it wasn't since the needle was moving down not up.

Can Renault explain what is happening to my car, where could the quarter petrol that was dispensed into my car disappeared to? I paid R299.75 for that quarter fill up and need to know where my money went to.