Why didn’t you know about the recall, didn’t BMW send you a notification?
The independent mechanic spent time troubleshooting your vehicle so he should be compensated for his time. Don’t forget, there is more to the labor charge than just his wages and benefits, there is the rent on the garage, utilities and the amortized cost of his tools and equipment that he is paying for.
Would you work for free, and put in your own money to boot?