Company blaming to join competitors asking money what to do

I had been working with a medical devices startup company and signed a service agreement of 3 lacs for 2 years for training to be provided along with joining for 2 months. The training was internal and no tutor was hired externally I did not get any certification not any study material for training given. Also the training was either designed by us the employees or from the previous job of my manager which was also confidential still he disclosed it as a part of training without the consent of his previous company. I left the organisation after eleven months. While leaving i stated i am joining other company which is in different line of work, now they have sent me a advocate notice saying I should pay 3 lacs within 10 days plus are saying I gave false reason for resignation and joined their competitor (but I have our last discussion on audio clip where they can be heard clearly listening and asking questions about the company I am supposed to join). I knew the people are with bad intensions. What should I do now?