Excess billing amont against regular plan

I was the customer of rcom since few years. Recently the company upgraded its services to 4G and without my approval they handed me a1100 monthly plan for whixh the bill should had been 1100at the end of the month but instead it came 1250 and 3500 respectively. I requested the company to give me the rational billing amount but they are harassing me to pay 3500. I even told them that it was the company’s responsibility to disconnect the services if i was exceeding my 1100 monthly plan usage but they are ignoring this and are admant on their bill amount. I feel this is cheating of Innocent customers.