WORST EXPERIENCE EVER!

I was letting a Huurkor flat in Pretoria North (SHARON'S COURT), but then got a offer in Capetown end of June 2018 (which i accepted). At the beginning of July a served a notice to vacate the premises and there was no response from them. I sent a follow up e-mail on the 9th of July regarding the matter. It is so unfortunate that now that i have left the premises end of July , i am now being informed that i will be liable for August rent, how possible is this? I am entitled to my deposit as i gave them one month notice and left the place in a condition that i found it in and was never in the premises from end of July 2018. I spoke to a certain lady by the name of Diana in the morning, who told me with attitude to wait for feedback for a period of 21 working days. Never saw this coming