Tata Institute Of Social Sciences — harassment from company

Address:

Mumbai City, Maharashtra, 400088

I applied for discontinuation of services on 08.05.2019 and have informed that i will be leaving the city on 09.05.2019. They told me that the process will take 10 days to which i agreed and told my landlord to wait for this much days for discontinuation of services.
It has been nearly 20 days, they are calling me daily harassing me every day with the same questions and concerns and not listening to discontinuation requests. I have no outstanding bill, still, i am getting messages daily that my amount is due.