Mts — Unprofessional way of communication

My device got faulty. I contacted all the customer service centres. They never even looked into it. I went in person to a few customer service centres. They were locked all the time. I have series of emails for all this. This happened 1 year back. Now, they are calling from Delhi with a rude tone claiming that they are calling from delhi court and threatening in a very unprofessional way. The guy who called is of name Pratap Singh with number : [protected].