MTS / Sistema Shyam TeleServices [SSTL] — Extracting fraudulent money

Address:	Jodhpur, Rajasthan, 342001
Website:	www.mtsindia.in

I had an MTS connection 4 years back and I disconnected due to pathetic service and extremely rude customer service. I was asked to pay the bill of 640/- even after disconnecting the service and they kept calling and harassing me and my parents to pay the bill even When i had stopped the connection. Just to stop the annoying calls I paid the amount got done with it. Year later we moved to another city and suddenly after 4 years they sent out an email that 253/- outstanding amount is left and if I dont pay the bill my connection would be disconnected and I can only pay 50% of if what is this nonsense Never ever use MTS
I also called the lady Kalpana Chaudhary who's no is mentioned in the email who was extremely rude to me and asked me to pay the amout of face the consequences and hung up is this a scam to collect the amout?