What a palaver. After filling in a claim form sent to me by Natwest mastercard found that it wouldn't submit. Called them back and went through the submission on the phone. The fact that they required each of the three transactions detailing (ST, Clubhouse, Parking) for service date etc, how much of the value was disputed etc meant a fairly lengthy call. However now submitted so waiting (10 days?) to hear if successful.
Incidentally I claimed for 12/14ths on the basis of games not played v games covered by ST, though now understand that at least one ST holder has had total cost refunded.
Thanks to Nelly for the useful info & links.