I've got one of those too...

06/05 IPPUDO AUSTRALIA PTY SYDNEY 73.87Let's compare my use of CSP:

06/06 PAPINELLE PTY LTD PADDINGTON 207.0106/07 PLINE PH WORLD SQ SYDNEY 37.7606/07 FUJIYA JAPANESE REST SYDNEY 69.60with my use of the Marriott Rewards Premier card:

06/08 GUZMAN Y GOMEZ WORLD SYDNEY 22.9506/10 COLES QUEENS PLAZA QLD 13.6406/08 MCDONALDS WYNYARD RAM SYDNEY 7.59The exchange rates on the Marriott card seem to be slightly higher on average than the CSP, and both rates are higher than the Visa USA rate of 0.936106 for June 9th. If you use the June 9th Visa USA rate, you'll get discrepancies for most of the posted transaction amounts. However, if I look at the Account Activity online, I see that all of the transactions actually have a Post Date of June 10th. If instead I use the Visa USA rate for June 10th, which was 0.936706, you will find all of the posted amounts will match if you take each transaction's AUD amount, multiply it by the 0.936706 rate, and round to the nearest cent. It's a bit cumbersome, but I believe this method should work when requesting credit for a forced DCC transaction. In summary for Chase cards:

1. Save your receipt and wait for the transaction to post to the Account Activity online
2. Use the Visa USA exchange rate from the Post Date and multiply the exchange rate by the amount of the local currency on the receipt
3. Subtract the result from the USD amount on your receipt to determine the dollar amount by which you were overcharged due to DCC
4. File a dispute with Chase for this amount and request a Reason Code 76 chargeback stating that you were not offered the option of paying in the local currency