Justsell property agency

I had a bad experience.. With just sell property agency... I put cacellations. That ill be moving out of the flat end of August.. And was liable to pay rent in july. Paying for August.. Currently they saying i need to pay rent for Aug how i dont understand.. And when telling them they can take it from the deposit they coming with the stories aswell. That the deposit paid for repairs n maintenance.. This agency they are *****ing people. And they sent an letter for demand. If m not paying they will summons