Broadly speaking, it's not economically feasible for an agency to take contracts that pay $7k (or even $25k, for that matter - I've written about this here https://bonner.jp/posts/the-co-op-consultancy/). So if they can do you a favor, in their minds, by fixing your whole website instead of just three pages - and if you're willing to pay for it - then everybody wins. Right?
That's the difference between a business relationship and being a friend: you may keep your mouth shut when a friend is being imposing, taking too much for granted, because you value the relationship. You would never remain silent in a business context when somebody is spending your money. It's business. They understand.
On my jobs, I'm explicit about what I'm going to do and what I'm not going to do. If my client needs to scale, I'm going to talk them through options for caching and horizontal & vertical scaling. But if my client seems to be dragging their feet on customer development and making poor business decisions about which features to prioritize, well, that's not my role in this relationship.
That said, I would never lead a client into a project backwards the way this agency did. Because I do value the relationship! In that I want you to come back, and pay me more money later. Not because we're friends. That's business honesty.
This situation is definitely your fault - but only because you and your agency had different assumptions about the rules or norms of your relationship. Your agency poorly communicated their intentions, and you allowed that to happen out of a misplaced sense of friendly obligation.
But hey, the new site does look great.