Insure-and-Go: we're there for you until you need us

How's this for a ripoff? We've got travel insurance from Insure-and-Go, which covers (among other things), flight cancellations due to strikes. Last summer, we bought plane tickets from the UK to the US for Christmas holidays. Some time in October, BA's union threatened a strike. On Oct 26, we renewed our Insure-and-Go policy. Now they're saying that if BA goes on strike this Christmas, they won't cover us -- they say that because "we knew there was a possibility of a strike" on Oct 26, we have no strike insurance (even though we were insured by them when we bought the tickets, and even though we renewed our policy on time).