Educational consultant for college admission, can I believe in them

Hi guys. I'm from cbe and I am in the process of admitting my sister in SRM KTR for aerospace Engineering. Me and my dad found couple of educational consultants from coimbatore and they are for helping us on the admission process and the process goes like paying the half of the payment to the college via their official link and some amount for the consultant for their process fee and they assure that my sister will get the seat and they told us the Entrance is for just formality and they assure we have the seat and my question is. Is this is Legit? And Ive also seen lot of students enrolled like this , is this way is good to go? And also how to find them legit ( because they still have questions ) and don't know how this works, it works like refferal. Any one did something like this for your admission kindly give me idea about the whole process and the legitimacy