Yes you'd have to go through currensea - from what I know their customer service isn't particularly good or bad as compared to UK banks, but they are not a bank so they won't just offer goodwill compensation payments to make you go away. They do apply their T&C strictly so you may not get points on certain transactions where you might have expected to get points.

Don't use it for any payments where the final amount to be charged is not known at the time of the transaction, and don't use it for subscription payments.