Quickly less time consuming process but after getting offer from recruiter they just don't respond to are further queries until joining date. There are two rounds of interview one being technical other HR round

I got an offer from August 5, 2024 and my joining date is September 11, 2024. But they are not onboard that same date. If I asking hr recruiter they said to some technical issue. Again I contact to hr recruiter, they are not responding my call and mail. I raised ticket again and again but no use not responding ticket mail also. So be aware of onboarding. They are giving false promise and offer letter