Ibm — Received offer letter but later not onboarded

Hi I got IBM offer Letter almost it took 15days to get and then before that only I resigned from my company as they informed me that I will get offer so on 5th may it's onboarding date and today 4th may last working day in my company but today they told me in BGV my company failed in verification how they can say because they all should check before providing offer letter I do agree with policies but they can't play with my job life I resigned because of them and now a day before joining they told this