Hakkoda interview questions

Got through 3 interviews 2 technical and one managerial. I was issued provisional offer letter and was requested to sign the final offer letter And was asked to resign before they release the final offer letter . The final offer letter came with incorrect joining date which I couldn't join on possibly. I requested the hr to change the same but she delayed and stopped calling me. Just 2 days before my current company's last working day I called them just to hear that the offer has been revoked and they can't do anything about it. They didn't have the courtesy to inform me and potentially risked my career over such a small reason. No answers and no apologies what do ever. Worthless company and team playing with people's careers.