It would affect your chances to get better college. If your OBC certificate is not valid/rejected implies then your counselling for medical college selection will be done according to your CRL (Common Rank List) rank. In case you believe that your certificate is still valid and some issues are there so don't hesitate to inform neet about this and report them instantly, here is the link where you can get contact details

https://ntaneet.nic.in/ntaneet/contact.aspx