talk to them, they say they have warned you before which they haven't, and now they are changing your duties.

I guess they are thinking if you have enough time to chat, you can swap the chat with some admin.

Anyway, If you really hate the job and can't see it going anywhere tell them this and if they don't do anything just quit.

I wouldn't be trying out your first business ideas just yet though, get something else and explorer the business in your free time.