Bosch Autonomous Driving - Planning/Robotics Research Engineer interview questions

05/31 applied online, 06/21 schedule 1st phone interview on 06/28. Received C++ test on the same day. Completed the test on 06/29. 07/05 sent an email asking feedback, 07/13 sent email again for the feedback, 07/19 sent email again. No response at all after I sent the test. I am pretty sure I did well in the test and he also asked my code samples. I spent hours to complete the test and sent the code samples, but I didn't get any response even after I sent multiple emails which is very rude. At least, I would expect a rejection email. They don't respect candidate. Very bad experience, don't recommend. What is interesting is that I know a guy working in Bosch, he promised to refer me. But at some time, he didn't reply to me too. I know two data points are too few, but why are Bosch people like to do these rude things?