The process at VFS office in new Delhi is seamless. Just show up with papers and submit them, they will verify if all in place and even consult you and advice you if any paper is short. You actually do not need any agent for getting visa for thailand if you use VFS directly as they are the biggest government authorized agents for visa of most countries. Go the right way and you will surely get a legit visa.
I think you already aware that all Indian Passport holders get visa through VFS Global and from India only. So get papers ready as per guidelines on this site here -
I am seeking visa for Business Purposes like business meeting/ signing contract/ project discussion and not for full time employment with salary in thailand. Please advice now.