Advocate Notice for Paying of Bond amount

Ive been recruited as a fresher by a Construction company in mumbai. During my joining company had made a to sign a bond that i must stay with company for minimum 2 years and if i fail to do so i must pay 2 lakh rupees amount for breaking bond. After completing 1 year of my training period i have been given a position of Senior engineer and they have issued a appointment letter to me where it is mentioned that if i want to leave company i have to serve a notice period of 30 days or give 1 month salary and there is no mention of bond or bond amount. After serving company for 1 year 10 months, due to family issues & unbearable circumstances i have resigned & spoke to top management where everyone were convinced & accepted my decision. I have served 28 days of notice period too. There is not a single penny balance from my side to company. After 8 months, today company had sent me a Advocate notice that i had to pay 2 lakhs within 15 days of receipt of this letter or else they shall take legal action against me. And instead of "bond amount", company had mentioned "Dues amount". Is the above mentioned bond Valid in India ? Should i send reply to company's advocate notice ? if yes how? What happens if i ignore this notice ?