Looking for a student job

Hi everyone! I came to Denmark to my mater thesis and was promised that I could work alongside my thesis to support myself. My residence permit allows me to work 90 hrs/week and my professor is also okay with that. However, the administrative office said I'm only allowed to work 14 hrs/week as per university rules. And they refuse to tell me the hourly salary I will get. I feel extremely screwed over because now, I need a new second job to support myself, so can anyone please recommend me possible student jobs or opeings in resturaunt/cafes. I am fluent in English and German. I would greatly appreciate any help.