Buying a cryptocurrency with a credit card is expensive, and AFAIK the online merchants who accept cards for digital currencies don't distinguish between credit or debit cards. The companies that accept cards are going to charge you fees to cover the risk of a reversal (remember if you reverse, the exchange rate may have changed significantly since the original transaction making their managing their cash flow much more complicated), plus you may incur international card fees depending on who the merchant is, and they're still going to charge you their normal spread over and above this.
(This is true for fiat currencies too - cash and cash equivalents are a special case of purchases, and can attract cash advance fees, reward exclusions, etc. Try reversing an international credit card payment some time, too, you can be out by as much as 5-6% in fees even though the charge was reversed!)
If you want to still want to go this route you could try buying Second Life Lindens (SLL) at e.g. VirWox and using those to buy Bitcoin (BTC) - of course you're going to pay the spread twice, making your BTC even more expensive.
(This is true for fiat currencies too - cash and cash equivalents are a special case of purchases, and can attract cash advance fees, reward exclusions, etc. Try reversing an international credit card payment some time, too, you can be out by as much as 5-6% in fees even though the charge was reversed!)
If you want to still want to go this route you could try buying Second Life Lindens (SLL) at e.g. VirWox and using those to buy Bitcoin (BTC) - of course you're going to pay the spread twice, making your BTC even more expensive.