Seven Hill Resorts — not receiving otp for applying gds post

I am trying to apply for tamilnadu gds post office requirement at 2020. Whenever i try to apply but cannot receiving otp for my mobile number. Further i cannot able to apply gor the post office requirement. I am tried many more times. But i cannot get the otp number for my mobile number. So please help me to get the otp number for applying the job.