How can i remove a lien from my property when the person holding the lien will not sign a Satisfaction of Mortgage form?

There is an existing lien on my property from 2004, which I just found out about. When I bought the property I had most of the money and I was waiting on cashing a Treasury Bond for the rest. For some reason the cashing of the bond was going to be held up for a couple of weeks. I informed the Realtor and he informed the seller. He told me that she did not want to postpone the closing and was willing to give me a short-term loan (a few weeks) so that I could make the closing. I agreed and signed a Promissory Note pledging to pay the loan back, with interest, as soon as I had access to the money from the Bond. The loan was for $57,500 which was due August 30, 2004. I paid it back on August 19, 2004 and thought that would be the end of it. Just found out that the seller never signed off. The seller now lives in England. I have written 2 letters asking her to sign the form and she has not replied. Also, I cannot prove that I paid the loan because I do not have the cancelled check