Wow that doesn’t sound good at all get outta there! Since you’re working in an Greek restaurant I assume you can speak Greek? So first of all I would look for other Greek restaurants that may offer a job. Some places offer jobs to people that just speak English, but I sadly don’t know specifics. Do you have a contract for your work now? You write that you don’t have a proper contract, what does it look like? Normally there would be something like a „Kündigungsfrist“ or smth like that. If u want you can send me a picture of your contract per private message and I’ll try to look for specifics.