Also want to share my experience in todays world of amazons and flipkarts and airtels and citibanks...am sure all of you have experienced it..but just want to list it so that it might help few people
(1) if you ever over use your broad limit or say pay late- just make a call to airtel or vadafone or who ever and just request them and tell them it is your fault and they just reverse off the amount..I have done this dozens of times over past 10 years..works for airtel, vodafone, citibank creditcard, icici credit card......hence all we need to do is just call and beg/threaten..whatever works and even the call center guy has the powers to waive amounts off..
(2) When it comes to websites like Amazon and hoping same for indian equivalents..they too are very liberal..for example..everytime i buy on amazon US...I take prime membership to make shipping faster and cancel it within 10-15 days..there have been couple of times when i forgot to cancel within 30 days..but i remembered later..I apologized and they credit my entire amount back
(3) last month, there was a 60 dollar drop on the pioneer fs52 floor standers 10 days after i bought it on Amazon US..policy says within 7 days they refund the difference..i still persisted, first guy on chat refused...after one day i tried again and second guy this time as a one time favor..refunded 60 dollars..someone from their service center in Delhi!
(4) Three days same thing happened on Amazon India this time..I wanted to buy the Panasonic FZ200 camera..it was for 26,499..it was appiness day..so I was happy to pay that minus 10% for HDFC card..when i was about to order..app said it was part of lightening deal..however when i clicked it..couldnt find it on the deal..so I called their india call center..lady was very helpful and said on her screen it was on offer for 23,999. so i tried again and this time price went up to 27700..i anyways ordered i. as usual i sent emails, had a chat, called up their call center again.
Finally yesterday the guy on the phone said he will give me 23,999 minus 10% for HDFC card:yahoo: i am waiting for the refund.
Hence moral of the story is that in todays free market world..all we need to do is contact these folks and usually they hear us and do the needful....we save ourselves few hundreds/thousands in this process.
Unfortunately there is no pennyfull app..or else I would have got 4% extra off

on 24K on the panasonic camera