Wipro — Delay for joining

I have received offer letter 2 month back form wipro and they given joining date 20 th of july and i will get release 15th of July my current company but now wipro HR they telling onboarding is holding.i don't know why they telling final stage and they didn't updated two month back and i don't have any options to go other.i have a lot of commitment and dependency.wipro is reputed company some people they are doing something to damage reputation.how it's happen joining date and release the offer letter even i didn't seen this kind situation in my career.Wipro please give the solution for this onboarding delay issue.