it will depend on your policy but if you're covered for 3rd party (or even accidental) damage then your insurers should cough up for your claim, then recoup the costs from your neighbour's insurers, without involving you. Unfortunately you may still be liaible for the excess, you would probably have to take your neighbour to small claims court to recoup that. Most insurance companies will only deal with the repair to the insured property, so the neighbour probably couldn't claim for your property on their policy anyway, even if you were both agreeable to that. I'd contact your insurance company again and be a bit tougher with them, providing of course that it's worth the £500 excess. If you're drying the property yourself (which I assume you are) don't waste a fortune just installing a couple of dehumidifiers and airmovers and leaving them for weeks, strip out anything that's soaking wet (I assume plaster and the flooring) then focus on the hard to dry materials such as brick. Anything else should dry out on its own quite quickly once the leak has been stopped. Good luck!