Munich has a number of German language schools. Most schools offer tailored, flexible and even one-on-one coaching but this of course comes with an expensive price tag. Intensive courses are generally 4 days a week, 4 hours a day and in slots of 4 weeks. There are also a number of evening options with courses twice/thrice a week. As a rule of thumb, there is generally a new course that starts in the first week of every month but this can vary from school to school. A number of schools also offer summer immersion courses and even offer to take care of lodging for a 4-6 week period.
For a complete listing of the various private language schools in Munich, click here
A more reasonable but effective option will be to contact the volkshochschule. These offer courses in one-month-intensive blocks at approximately 150euros a course. For more information, log onto http://www.mvhs.de/