Big Bazaar — deliberate wrong billing

I shopped at Big Bazar at City Mall at Nasik on 8th Feb 2015. Bill details...Till No- 13, Cash Memo No..0022396 Tr:3036, CH:17422, Sudesh Gore... Total Bill- Rs 3429.19/ In this I had purchased a Mustard oil 5 litre pack . MRP on body was Rs 660/ On going home I find the price on the bill as Rs 725/ I again drove down to the store and got it checked. Quietly and meekly they accepted the mistake saying thet it was double billing mistake and gave me the refund money which was a meagre amount of Rs 65/ But this open up a pandoras box... 1- Pantaloon stores cannot be believed on because they could do billing mistakes. 2- This could be a deliberate method. 90% of the customers do not check bills. This is the first time I did. Bills are so confusing.. And all are not educated... 3- people go to renowned stores not to be fooled. They believe in what computerised information/prices are given. System always take care. 4. The bill does not say... We can make mistakes, our people/systems are poor or bad... Please check your bils for applied discounts.. check each items with the prices written on the body... That's atrocious. 5.. And who pays for the car petrol I spent to get my refund?? 6- My complaint lodged at the stores... Share with us..No 31 .. On lodging the complaint at the stores I also did not find the complaint desk to be positive and good. They were acting as if I did a mistake in showing this wrong billing. 6- Finally what are going to do about this.