Originally Posted by
Starbucks
Whole T&C as printed on the back of those vouchers below:
I did not check the accuracy of Natixis "Multidevises" en detail but it seems that if you can get the hotels to follow their own t&c stated on the coupon in regard to the exchange rate used their margin to gain an additional 10% is limited.
If you want to really confuse them, bring both EU and USD vouchers!