The minimum amount that can be set for a transaction is set by the card endorser (Visa, MC, etc.). Visa accepts a $0 transaction which can happen if they are trying to verify the account (found this out from my bank last year when tracking down an issue). Don't know about the others but some may have a $1 minimum. Not sure if Visa/MC/whatever have different limits for different countries. At least in the US Visa uses $0 for account verification transactions (and Turbine is a US-based company). The bank should be following the rules setup by Visa/MC/et al and not changing them.
Now, if Visa/MC/whoever has a $0 transaction for the US and a $1 transaction for the country you're in, that may be where the problem lies. Turbine, being a US company, follows the US rules and sends in a $0 transaction to verify the account. Their processing company (which may or may not accept any other amount) sends it up the line until it gets to your bank. Since no one along the way will change the amount from $0 to $1 (and I wouldn't expect any of them to) your bank sees what they consider an incorrect amount. Turbine has sent what they consider the correct amount. Everyone did what they were supposed to do but since they are not using the same rules to talk to each other it fails. Not sure if this is what is actually happening, it's just my best guess.
As Yula said though, you'll need to talk to Turbine to get this resolved. They can do a manual transaction to get it to work when the normal means we have to use fail. Also, see the sticky Alternate Ways to Contact Account Support (particularly for International Players) for calling them overseas for reduced rates/free.
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