Thanks all for your feedback. We've flagged to Microsoft and they seem to understand what the problem is, so hopefully it should be corrected shortly.
As some users have pointed out, you should be able to pick RBN tracks up Xbox.com, so that should work in a pinch until Microsoft gets things straightened out. We'll update when we hear back!
Unfortunately I have found out that this method is impossible given that as the MSP gets converted into local currency, you will always have a MSP total of 0 when on xbox.com (I tried redeeming a 2100MSP card on the site and it automatically converted to local currency still meaning 0MSP).