I would take my machine to another dealer for a tune up. There is no reason you should be having these problems.
I have had Berninas for many years and have never had any problems with any of mine.
But I do take them in every few years for a good cleaning and a tune up. And I clean my machines with q-tips after every quilt. have you taken the throat plate off ato see if there is any thread caught anywhere?
Have you checked to see if you are threading the machine correctly?