Having used up my data cap my browser uually routes me to the buy more data page on the vodafone website where I can pay $15 for another 20GB.
http://www.vodafone.co.nz/myvodafone/ng/buy-more-data?landingUrl=upsize-rbi
However this month I now get a popup browser window saying

Please turn off Wi-Fi
Whoops! Seems like you're on a Wi-Fi network. We can help you better when you're connected to our mobile network. Please turn off your Wi-Fi and try again.
This is a daft suggestion as I'm connected to my RBI modem via wifi, If I turned it off then I wouldn't be able to connect to the website. It looks llike a piece of code intended for mobile phone users has been applied to Rural Broadband users.
I've tested in multiple browsers in both public and private modes. its consistent.
I had to call vodafone for 30 minutes last night to get the data extended - it still has not been done.