Company relieved me without allowing me to finish notice period

Hi, I had been working in an IT company from July 2015 to 6 October 2016. I resigned from the job due to extremely low increment in salary. When I resigned the management voluntarily waived off my notice period and relieved me from the company on the second day of resignation notice saying that I will be paid two months basic salary in lieu of the notice period. Normal notice period is for two months, though the offer of employment states that either party can terminate the employment by paying two months notice or two month's basic salary instead. I feel that I am entitled for the full salary in lieu of the notice period as I never requested for the waiver. They did not even talked to me before deciding on my last working day, my manager replied to my email stating that October 6th was my last day with the company, whereas I requested them relieve me on November 30th. Please advise me what can i do