Flaky USB ports on WD15

I've had my WD15 for 10 months and it has been as frustrating as all heck. It took me nearly 8 weeks to figure out how to get the BIOS etc updated, firmware installed etc because it came with no useful instructions and the guides that are on the Dell website didn't exist at the time. The thunderbolt dock, which I wanted and was available when I bought my laptop at the end of July 2016 was withdrawn from sale when I ordered the dock, so I settled for the WD15. It has been a nightmare!

Over time, the USB ports seem to have become progressively less reliable (although they've never been flash). Tonight, I followed the WD15 instrutions and installed the Dell Command software, which downloaded a few extra updates, a few of which repeatedly failed. This led to BSOD errors, Dell recovery, system resores etc etc, which wasted nearly 4 hours.

The Tag number on teh bottom of the dock isn't recognised by the dell warranty status system. What options do I have? Googling, I don't seem to be alone with my poor experience of dell docking products.