I accepted an offer from two companies at the same time. I served a three-month notice period in my current company. Two weeks before my joining date, I informed the first company that I would not be able to join them as I would be joining the second company. The HR from the first company threatened to blacklist me in NSR, saying that I should have informed them when I received the offer from the second company, and that two weeks before was not an appropriate time. Are they not forcing me to join their company?