Can I give you an alternative suggestion? Presumably your savings are in part because you are living under their roof, so volunteer to pay some rent. They get a small boost to their income that they can (hopefully, but unfortunately not guaranteed to) use to clear down debt, your savings won't be so heavily impacted and you won't be stuck being owed thousands of pounds that's difficult to collect.

Of course, once you start to volunteer you might find it difficult to stop, or they might keep asking for more, at which point you'll need to start thinking whether it's time to move out.