Can I pay in advance loan?

Can I even prepay my loan? It's such a rip-off, you know? I try to pay extra, thinking, "Great! I'll knock down the principal, pay less interest overall!" But no. It just sits there. Like a credit, they say. A credit! Isn't that supposed to be a good thing? But it doesn't actually lower what I owe right now. It's like they're holding my money hostage. Just waiting for the next payment due date to roll around. What's the point? I'm literally trying to give them more money, to save money in the long run, and they're basically saying, "Nah, we'll just keep it warm for ya." Remember that time I paid off my car loan early? I was so proud, felt like I'd accomplished something! This is the opposite of that feeling. It's just... ugh. It feels like they're intentionally making it difficult to save on interest. Seriously, is this even legal? It feels almost predatory. They're getting their interest payments either way, right? So why not let me chip away at the principal? It's so frustrating!