Thank you for your question
My name is Clare
I shall do my best to help you but I need some further information first.
For clarity - you own a property with someone else.
Is the other person willing to agree to this?
How much is the house worth and how much is outstanding on the mortgage?
Why has the property dropped in value?
Has the mortgage company agreed to release you?
Did you protect your investment with a Declaration of Trust when you purchased the property?
Are you sure about the current value?
It is worth checking as otherwise you are correct - the offer of £40,000 is indeed the best that you can hope for I am afraid
I am afraid that you cannot claim any back rent - just your share of the equity
Please ask if you need further details