How to close a American Express credit card permanently?

I've owned 4 cards over the last 7 years. The biggest lesson: a card that fits your spend pattern beats the 'most rewarding' card on paper. A 5% cashback card you actually use daily will give you 10x more value than a 10% card you use once a month.

Forex markup comparison: Amex = 3.5%, HDFC Infinia/Diners Black = 2.0%, Axis Atlas = 3.5% but with milestone fee waivers, ICICI Emeralde = 3.5%, Standard Chartered = 3.5%. If you travel more than twice a year, the math favours Infinia or Diners Black.

Dispute process that worked for me: I called customer care within 24 hours, raised a dispute via the netbanking portal (uploading the receipt showing I never visited the merchant), and got a provisional credit in 5 working days. Permanent credit came after the bank's investigation in about 30 days.