I failed my 70-646 this week, so I rang Prometric to use my previously arranged second shot registration to book a re-sit before the end of June.
They tell me that my second shot code has been used by someone else

I have had to refer this to Microsoft and do a screen-shot of the online booking error.
Anybody had similar problems ??
In addition to this, all the local test centres seem to be fully booked for June, so its travelling time