Indian Oil Corporation [IOC] — "Accidentally" filled more than we asked for

Address:

Devaraj enterprises, Green glen layout, Bellandur

I had gone to Devaraj Enterprises, Green Glen Layout, Bellandur, Bengaluru this morning at about 7am and asked for 500 petrol. The attendent (nagaraj) started filling the tank and didn't pay attention. When I looked at the meter, it was 2570 when I banged at my door to get his attention and asked him to stop. He went and brought who, I assume, was the manager and another man. They apologized for the "mistake" and asked if I was paying by card or cash. When I told him I was not going to pay for the extra and that he should pump out the extra, they refused. We talked for over 10 minutes regarding the same but one of the managers (dhanapal) starting calling me a cheapskate for not paying and leaving. He said I can pay little by little in three days. I insisted he pumped out the fuel but he got angry and walked away mumbling that we are creating a problem instead of just paying and leaving. We paid 2570 and left. In their defense, the manager said it was Nagaraj's first day at work. Why was he allowed to handle customers of he wasn't fully trained? Why is there no option to pump the extra fuel that was accidently put into the tank? Why should I have to pay for someone else's mistake? I don't know if this is a regular practice there but this is wrong and I would appreciate immediate action. Thank you