Thanks for your enquiry.
Even though the property is in your sole name, and hence you are the legal owner, your ex partner has what is called an "equitable interest " in the property, meaning she has made a financial contribution to the property, being £10,000.
Although I appreciate you have been left with all the Bills/Mortgage etc, the day to day bills are expenses you are incurring, she has contributed £10,000 towards the purchase price of the house, and it would be unequitable (unfair) for you to in effect walk off with this money/contribution.
Your ex partner could issue court proceedings to claim her money back.
I am sorry this is not the answer you were looking for, but I am just setting out the legal position.
If I have answered your question, I would be grateful if you could leave positive feedback.
Thanks for your reply.
You are correct in that if she went to Court, it would be her word against yours, but no doubt she would be able to provide evidence by way of an old Bank statement or other, to show she had made this payment.
Of course, you may want to chance your luck and hope she doesn't take any Court action, as this will be expensive in itself, but I have tried to give you the legal overview, for which a local Solicitor would have charged you a lot more.
Please feel free to come back to me if you need any further clarification.
Your issue has nothing to do with the above Act, which deals with Contracts/ agreements for Sale between a Seller and a Buyer.
Your ex partner has an "equitable interest" in the property, just like your Mortgage Company has a financial interest in your property.