My gredit expert

Hello everyone I'm concerned about my credit expert. I was have 594 credit score, I send everything to them and the settlement letter, instead my credit score to increase to 604 it's decrease to 584. So my problem is I don't understand how they work or the system work and they said I need to open an account or credit card there's no any company or a business, that want to open the account with that score of 584 so how am I going to increase my credit to 604(good) thank you