Don’t know why I didn’t think of this before, still waiting for my prepay card and barcode to be sorted, however worked out why not just generate your own one? Well it works even tested a barcode app on Android phone and it works, it’s just your prepay card number in a barcode.
Just put your registered card number into this (without spaces or dashes, just numbers!) and you can save the barcode to your phone or print it and use it to top up with :-)
Use this at your own risk, always double check the number and always keep your receipt with the VEND code on!
Hope this helps