I just recently got mine (just over the ditch from you) and was successfully able to use POS from credit account.
It took about 24 hours for the money load to go through onto the card.
I beleive that you will definately need to hit credit so that the transaction is routed via the acquirer bank to Mastercard International.
If you hit cheque or savings then different rules take over, and you should have go an unrecognised account error.
Are all the response for all three accounts the same? or is credit different?
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Having said all that - try going online to the card site - and initiating a chat with their helpdesk as they've got all tools needed to work out what happened.
I found them very helpful when I was setting up my card last week.
