Since this is likely to be a painful process, thought it deserved its own thread to see how people are faring and any tips to get this to happen.
As hippy_smell pointed out in the other thread:
ATP say "Refunds will be available to all customers at the point of purchase." (http://www.atpfestival.com/events/news/1408121314.php)
Dash Tickets says: "In the event of a cancellation Dash accepts no responsibility for refunds. Customers must request refunds directly from the presenter." (http://hq.dashtickets.com/terms-of-sale-usa/, point 4) thought that link says "USA" and 8.2 states "Occasionally, events are cancelled by the presenter due to circumstances beyond their control, such as weather conditions. Should this occur, please contact us for information on the procedure for receiving a refund for your ticket(s)."
So far I've emailed both of them, but I'm not expecting a reply any time soon, but will update here when (or if) it happens.