Then take a look at the Bildungszentrum in Nürnberg.
The Bildungszentrum provides a number of German courses for foreigners which are titled “Deutsch als Fremdsprache”. These courses last usually 2-3 months, but there is also the option for intensive courses, which can be completed in a matter of weeks. All are subsidized by the city which means that a typical 60-hour course would cost ~180 € . The class sizes are normally restricted to a maximum of 18 people.
No courses involve a lot of coursework, but fortunately no exams. On completion of the course the student is presented with a certificate as a proof of their attendance. This is particularly useful to hang on to, particularly if you ever decide to apply for jobs, residency or citizenship in Germany.
Most of the courses take place in the early evening, so as to make it possible for people in full-time employment to attend them. Courses are usually held in various classrooms at various schools in different locations within the city. All of these locations are normally easily accessible with public transport.
Check out the courses here:
If you have difficulty understanding German on the website, then ask a German colleague nicely to look at it with you and to help you book a place on a course.