While i understand your frustration, that is still largely irrelevant. Fact is, you tried to get a cheaper price by doing this with the worker directly. Thats not how services work and you should know that seeing as you previously hired Hope's AIO to do a service for you. When you were approached by the ex-worker, instead of doing what you did earlier (Ticket -> Pay Hope etc..) You decided to deal with him directly because he was cheaper. While you might've been under the impression that he was one of hopes workers since he had recently completed something for you, if you had bothered to check the server before assuming so, you would've seen that the user was no longer part of Hope's AIO team.
We will not be holding Hope responsible here, this is largely down to your clumsiness really.