Company asking for payment of one month salary for notice period

Hi Sir,, I was working with a MNC. I worked there for around two years. On medical emergency I have left the job (as my daughter,4 years of age underwent 2 bypass surgery. For her further treatment I resigned from the job.) Documents submitted to the concerned authority. Instead of two months I served 1 months’ notice time, which was approved by my COH verbally. As per 1 months’ notice period my last working day was 29th July. In between I asked my HR will I be relieved on 27th July?? I even asked if there is any salary recovery from the company’s end if I relieved earlier (Im having the copy of this mail). I didn’t get a reply to this mail but my relieving date was preponed to 27 July without any notice to me. When I called my Manager on 27th to inform him that I will be on leave on 27th July, It was told that 27th is my last working day. They would have never inform, if I have not called them. Now the issue is that company is asking for recovery