if the payment was rejected:
there is a small fee for converting CAN$ to EUR$ or GBP$ etc... i don't know exactly what it is... i bought 10$USD worth of dreamhost hosting which would have cost 11.72 CAN but 12.12 was charged to the card
so make sure the total doesn't come RIGHT up to 28.80, take into account whatever percentage that fee is
*edit*
i think the fee is between 3 and 5 percent of the purchase price in canadian dollars. eg,
47.00 GBP = 106.40 CAN = 111.43 actually charged to the card
if possible, order from a canadian site. haha