Legal Question in Real Estate Law in Virginia

Re: Landlord-Tenant issue

It's unclear whether you have a written lease or oral agreement. If the latter, it could, of course, be modified orally, but such modifications, to be valid, would only operate prospectively rather than retroactively, meaning the landlord,

once having agreed to reduce your rent(for whatever reason), could not come back to you three weeks later and demand the difference between what you had been paying previous to the modification and the reduced amount of rent. She could, of course, increase the rent to what it had been before, assuming your agreement.

If your security deposit is now being held to pay for these "back rents", you may wish to consider filing suit in small claims court at the appropriate time to recover from the landlord any amounts which may have been improperly withheld.