I think the likelihood of you getting a raise is pretty low, since it’s a contract between the agency and the client. I think the best you can do is explain, politely, to your agency that the scope of work you are responsible for is different than what you were originally contracted for. It’s up to them to decide if they want to renegotiate with the client, and whether or not they pass any additional compensation your way.

Without knowing the terms of your contract, I’m going to assume the agency is for placement only, and all the actual technical stuff is on you. I would be careful describing your work environment in the same way you’ve done here with anyone irl. You definitely come across as rude, because you don’t offer any respectful comments about your colleagues and it’s everyone’s fault but yours. Even if that’s 100% true, that everyone else is literally dropping the ball left and right, you can still find more effective ways to tactfully explain the situation and get your agency and their client on your side.

Being technical requires extra effort with soft skills, because not everyone sees the challenges you face in the same way. You need to communicate respectfully with your colleagues and find ways to get your message across is a less bitchy way so you get the support you need.