Have you tried clearing browser cache, trying a different browsers and trying different devices? You have the option also to pay by calling *123 and dial option 3, pay via online banking if you cannot get it to work.
We got your payment! I see you used #123 as per Goran's recco. We'll look at your sessions to try to see what may have happened, but on our end I can see thousands of payments coming through so it seems to work.