The issue of termination is important, because it discloses what kind of contract you actually have. I know they aren't trying to terminate you, but if you have a contract which doesn't stop them from terminating you, then they can literally terminate your employment and then immediately offer you new employment at the rates they want.
Just because is says the words "Employment contract" on it does not mean that it meets the legal requirements of a contract. I can understand you having a hard time believing this, but I make a living interpreting and drafting these things. It's all I do. I'd love to be able to tell you that you have an ironclad employment contract here. I would if I could. It'd make you happy and you'd be more likely to pay me. And yet, I'm not simply telling you that. The reason is that I'm being honest with you here.
Yes, a true employment contract has to be of a certain degree of complexity. That is why attorneys draft these things. What matters is the contents of the contract, not what someone decides to label it. Plenty of employers label things "independent contractor agreement" but the contents of the document make it legally an employment contract.
Now, I'm not saying that you do not have a legal argument here. I'm not saying that you can't use this agreement that was drafted up for something. Yes, a court would be willing to consider it an attempt at a contract, but it will have to use its equitable powers to do so. I'm not going to try and teach you the entirety of contract law right now, but there are two sides to it....basic contract law and equity.
I'm saying that under basic contract law, that is not an employment contract because it does not limit the employer's ability to terminate the agreement or you.
Your arguments will have to be under equity and that swings on you having relied, to your detriment, on their promises. The laws of equity are concerned with making that which should have happened, happen. This is where you'll have to make your arguments to enforce the agreement that you have.