if all else fails i guess you could cut her water which i assume is in your name. i can only assume that this would be in breach of the tenancies act and you may be fined for it but i think most people would move out pretty quickly if they dont have running water. the potential fine may be worth it.
Rockstar if tribunal rules in her favour you will certainly be up for any costs incurred by buyer due to you not
settling on time
Best wishes, sounds like a messy situation. Did you receive any legal advice prior to entering into this arrangement?