They wrote earlier to inform of an adjustment on my account. On logging in, my balance now reflects the bet being settled as a winner. In essence, their response is through that action rather than an answer to my query on the rule behind voiding on such a scenario. Sorry I can't provide anything further but I think it's raised an issue I, and maybe others, might not have thought about with action bets.
Again, thank you to everyone who contributed to the discussion.