Get a big angry dog, and starve it. The downside of this is that you'll never be able to get your bikes out of the shed again.
Alternatively, sell the Mojo and buy a Saracen.
We're with one of the various RBS shill brands but they still only go up to £3000, and i have to be honest I'd be a wee bit nervous about their claims process, they seem a bit vague. Also, though the bikes are covered to their specific value, that also counts towards the single payout limit of £1000. So, we'd get the payout for the bikes but effectively nothing else in the garage is insured, which is a bit worrying.