Rent arrears

I have court order in Dec 2009 to evict my tenant if she did not pay rent+past arrears.She is now behind in payments. I found out that she sub-let my property without my permission and collected rent as well as £2,900 deposit. I challenged her about this. She promised to pay all arrears and vacate by April 29th. When I was away oversaes last week She vacated my property and took the keys. I sent her a sms. She replied she would post the keys.But she said she has no money to pay. She is employed with good income.

Her tenant is in my flat now. He is willing to move out within 48 hrs.

I have found that she moved her things to her mum's place. I found the address. In eralier correspondence I was told She is planning to leave the country on 29th to USA on work and she is likely to come back only in Nov 2010.

What action should I take? Could I ask the court to posses her things at her mum's. Could I ask court to freeze her bank account. Please advise.