I was guarantor of a person X for a commercial vehicle loan in 2011 for tenure of four years. Person X was well known to me and installments were up-to-date. The X is not paid the amount for two installments, financier seized the vehicle, and sold to Y. Financier neither informed me nor took my approval to sold the vehicle to Y who was unknown to me. After 2 months, financier approached me and asking me to pay the differential amount (Actual expected amount - actual sold amont). The financier is calling me for my time to sit and will and discuss. What can I do now?