Non - compete agreement

Hi, My previous organisation has served me with a legal notice to me for the breach of non-compete agreement and now they are not releasing my full and final settlement amount as well as relieving and experience letter. The usual FNF time is within 60 days from the relieving date. There was no response from them for quite long. When I started rigorous follow-up after 80 days they served me with a notice that I am not supposed to serve in a competitive firm. To be clear my new organisation is 20-30 times larger in value and over 15 times greater in strength to my previous organisation. Can this even be termed as a competition between 2 organisation having such a vast difference. They have asked to either drop my job or pay a hefty amount to them which is in lacs. They do have a clause in their appointment letter that an employee is not supposed to join a competitive organisation but they haven't provided any list any where as to who are their competitors, this leaves the point open ended. Does this mean I cannot pursue my career anywhere in the same profile? And, what is that I can do now and what are their options?