If you can get someone who actually understands English (due to the o'seas call centers), the first thing you'll probably hear is silence, followed by not much help, if you are in your first year of having the card.
If you've had the card more than one year, you will probably get questioned rather sharply as to why you need the interest reduced. It's theoretically possible, but usually only offered under special circumstances, such as a pending default or other financial woes.
If they do choose to work with you on this (and I don't hold out much hope), you may see your current limit lowered at the same time, or get a phone call from Amex upon every transaction over a certain dollar amount.
TBH, if the interest isn't what you are willing to pay, you will probably be asked if you'd like to switch to another Amex card, or to another card altogether.
I know there are lots of websites which mention doing this to all your card companies to save on usurious fees and such, but with Amex you can usually forget it. Sorry to bear bad news. You can try anyway - I could be wrong and you might save some money!
