Double Check Bills .......before paying.....!

Yesterday i was having my dinner at a restaurant in Queensbay. There were five of us and each of us ordered different set of meals plus drinks. When it was time to pay, i asked the waiter to bring the bill. In my hand , i had a 100rm note expecting it to be within that range for my meals...but when he handed me the bill i saw the figure rm 130++...so instead of digging more notes from my purse i place my credit card on the bill...but on second thoughts i ask son to double check the bill before he could slash my card......my son noticed the word 'coke' on the bill which we did not order....so it must be the wrong bill....how careless of them! So better watch out next time....when he later he brought back our correct bill, the amount was just rm 97++ ...Nearly overpaid for our hard earn money....