Do you owe the money?
Have you spoken to them about a payment plan?
Oh yes, but that doesn't mean they cannot write to you there unless, of course, she has provided a forwarding address and you have been in contact to confirm that you do live there.
I'm not sure what you wanted to achieve really? Obviously the debt will not go away. It will be easy enouh to get them to focus upon you if you give them your up to date address. Then she could just ignore any correspondence.
They cannot attend at her property without a CCJ anyway. They could get a CCJ and send bailiffs to that address unless you provide a new one.
Even then they cannot remove goods that do not belong to the debtor.
If you just want them to write to you then just update them with your address and that should be the end of it.
Can I clarify anything for you?