Be honest – explain to them it is only a scam and it will harm their SEO position. And that in exchange for paying them $75 your client will give them all their logins and access to all their Google, Twitter, Instagram and any other media account they might have; and they will fork over their credit card number.
The writing they will give you is 100% plagiarized, the language structure they will use is Hindi-glish, and the damage they can – and will – do might be almost unrecoverable.
A scam is a scam is a scam. Learn how to recognize them.