What is the legal validity of a Non-Compete agreement in India

Hi, I was working with a India based startup IT consultancy(A) from oct 15 - June 2018 (around 3 years). During my tenure there, the startup IT consultancy had a MNC as a significant client. In June 2018, I chose to leave the startup and joined another B consultancy & this B company has deployed me at MNC for 6 months of period & after this period they will assign me somewhere else. Now where I've deployed at MNC that is still a client for the startup consultancy (A) I was working at. The problem is that the startup claims that I was made to sign a 1 year Non-Compete agreement, that I am personally unaware of. However, now the startup is threatening to take legal action against me and holding my salary FnF, only because I've deployed at their MNC client indirectly. The startup claims that the Non Compete agreement is valid for 1 year and if I join n deployed at the MNC, I will face legal action. My question is, will this non compete agreement be valid, since I've joined B consultancy n they only deployed me at MNC. Even I do not have any agreement between me &MNC. Now startup is not entertaining my BGV verification & held my salary & FnF and kind of poaching me. Harassing me &making me afraid of legal action and it's affecting on my mind & concentration at work often. If I indeed face legal action, under which act will the case be drafted? As startup consultancy(recruitment) and MNC(big IT) there is no competition at all. Pls help with some suggestions.