Should be no problem. As HK Citizen, you should receive a Visa Free 45 day Entry. However, remember that since you won't have a Visa, you may be asked to show 20,000 Baht and Flight Ticket out.
You are a Fool, if you go for such a Scam. I don't believe any so-called "Agent" can "get around" the legal requirements. And, even if they did, it would be fraudulent, and if you are ever discovered you would be fined, possibly jailed, and definately deported. AND, instead of simply investing your money in a safe Thai Bank Account earning good interest, you would be "pissing away" 15K Baht or more?