how do I get a china visa without paying agents 350 thousand naira

Nkechi, if you don't want to pay for the agent, you can do the applicatiom by yourself.

You need to apply for an M type.

Firstly, prepare the following documents in advance:
1. One completed application form (V. 2013) with a recently taken passport photo stuck on it; 2. Photocopy of your passport data page, the passport should have at least six months of remaining validity and two blank pages; 3. Original invitation letter of duly authorized unit or confirmation letter of invitation issued by the Chinese government departments, companies and social organizations authorized by the Foreign Ministry; 4. Invitation letter issued by a trade partner in China; 5. One formal introduction letter from your company to tell your identity, the purpose of visit, and supposed duration of stay; 6. Photocopy of your company's certificate of incorporation; 7. Latest six months' bank statement of account with at least 4 million Naira in deposit if you come to China for the first time; 8. Any other documents which the consular officials view necessary.

Then submit the documents to the embassy and make an appointment for the interview.

Lastly, go to attend the interview on the scheduled date.