Firstly if any Bangalore petrol pump guy is reading this thread he would straight away pack his bag to delhi....
as mentioned earlier do not get distracted even if some one is asking you for money or anything while petrol is getting filled....from so many years this is a common practice in bangalore and there have been many mails about this also.
For bikes make sure that you fill in small amounts so that there is less scope for cheating.
Have you anytime complained about this to the owner or Indian Oil because once I had a doubt that the petrol was not filled properly (Properly in the sense my car petrol indicator was showing low even though more than half of the tank was filled) and I complained it the manager there. He immediately took a 5 liter can filled it in front of me and later I realized that my cars fuel indicator was not working properly. Every one may not have the same issue but can still try complaining first.