My A4 has recently developed a creaking, almost knocking noise coming from the drivers side B-pillar area, towards the lower end (Seatbelt pillar) - More noticeable on braking & lower speeds & after driving for some time, it has slowly gotten worse over the last few months. I have taken off the trim, and everything seems secure . I originally took it into the garage to look at, but as the sound is only apparent when it has been driven for a little while they couldn't diagnose it. Any ideas? I can try and take a video or record the noise if that helps.