RBL Bank — Demanding payment which was already been paid 4-5 years ago

HI, in the year 2017 my father purchased a smartphone using rbl card and emi feature with a 12 month.the amount was cleared and my father took the photos of cheques aswell.Now after all these year today i received a msg from them to pay the amount 9962 and a legal action had been contemplared against him and the sender was qp-legalb. They have called some years back but due to very bad language issues we blocked their number. What to be done here?