Due to the weather on Sunday at the Japshow Finale at Santa Pod, they havd applied a "Rain Off Policy" against this event.
Therefore, if you still have your ticket from Sunday, you will be able to offset this against another event at Santa Pod. See here for details.
http://www.santapod.co.uk/g_rainoffs.php
Please note that to exchange your tickets you will need to do this direct with Santa Pod and not via MRC.