Cancellation of Texted "Agreement" to Return Deposit

Tenancy Deposits

We have a problem tenant (who has signed a standard RLA agreement) who has now announced she will leave on 27/03, therefore giving us only about half the required minimum notice of one month. Her deposit was properly protected and prescribed information properly served.

The tenant yesterday demanded (by text) our return of her full %C2£1000 deposit within two days of moving out (to which we texted %E2%80%9Cnoted%E2%80%9D, in the relief of the moment). In a previous notification to leave, we texted %E2%80%9Cagreed%E2%80%9D to the same proposal, although she subsequently cancelled her notice on that occasion.

However, after a more dispassionate examination of her tenancy account overnight, we calculated that she owes us around %C2£800 of her deposit in (1) rent arrears (both current and to make up the shortfall in notice period) and (2) other miscellaneous bits and pieces.

We therefore wish to check whether our texting of %E2%80%9Cagreed%E2%80%9D on the previous occasion and more studiedly %E2%80%9Cnoted%E2%80%9D on this occasion constitutes a valid agreement in law - and if indeed valid in law, could this be successfully rescinded before her move out?

Could we argue that our "agreement" (if a valid agreement in law) was given only on the basis that no legitimate deductions to the deposit (under our written agreement) would be available to us?

The situation may be further complicated by the fact that she has since advised us that she has now signed her new tenancy agreement (presumably on her understanding that we had irrevocably agreed to returning her full deposit.

Please advise.

Forum comments welcome.