charged for Fuel, which is not for my account

Good morning I have been renting vehicles from Woodford Hatfield, and only received excellent service from them. However, suddenly last week they have charged an amount of R649.40 for fuel, a month after returning a vehicle. Sadly, the last rental was only for one day, and I refuel at the garage by the Woodford Harfield branch and handed in my fuel slip to the value of R206.60 for around R140 KM driven. So, I am not sure, why a month later my credit card is charged this amount of R649.40. This is such a frustration, as this is definitely not for my use. It is also a concern, that this amount is charged to me without my approval. Thus, their excellent rates for me are now down. it is something all renters need to be made aware of.