Trainline NET Developer interview questions

I applied via an agency. They sent me a tech test which was refactoring a class. I did it very well but they come back with a non constructive feedback which says the code was not at our standard level. but why ? where it was not standard ? I think when people spend time and do a test for them they have to respect people and give a feedback, at least a persuasive feedback. This is not fair to say your code was not standard enough. Specially at our level, I mean senior, we have our own explanation of choosing a method or an approach they cannot just say it was not standard enough.