Yeah it was rough trying to figure out what Miu was saying here with the negatives mixed up. I think it's supposed to read "The other day, when those people from the company came... If Sawada had stopped them with everything he had," which makes a lot more sense. It makes it easier to understand why Miu is angry.
The bubble on the next page saying "Sawada was the only one who managed to prevent it beforehand" is probably also wrong, since he didn't prevent them from showing up. "Sawada was the only one who could have managed to prevent it beforehand" makes more sense, but I don't know what it says in Japanese.