Just cancelled my sub and then repurchased. Pricing is correctly displayed.
Double check your invoice/receipt? - You should not have been charged GST on the gift card. I sell gift cards in my company, and no GST is chargeable on gift cards themselves. GST is charged at the time of purchasing the items that you pay for your gift cards. The gift cards are, in effect, cash. If you had a 19.99 gift card for Zwift, eg, you’d have $19.99 to redeem. The monthly cost is AUD$19.99 PLUS GST - so the cost is AUD21.99. Your card is $2 short - hence the extras.
Has anyone received an email about the change? If so please can they post it. I’ve searched my notifications from Zwift and can’t find anything from July 2019 about being able to pay in AUD. I’m paying US$16.49 which is AUD $24.81 via Paypal. How long does it take for the membership to be cancelled - does it run to the end of the payment period or is it effective immediately?
The email explaining the addition of taxes to your subscription should have been sent out several days before the first charge that would have been affected. More information on the change can be found here.
As for the option to pay through non-US currency, that was added a while before then. The system wasn’t able to automatically switch you over, but canceling and starting a new subscription should fix it. In case you need instructions for canceling, that would be here.
Additionally, your membership will continue until the next bill date regardless of when you cancel.