For all those new to the X5, the window regulators are the worst part of the car. Always keep one of each window regulator on your garage shelf and learn how to replace yourself. Will take a few times doing it, but will save you a ton of money and hassle having your window down while parking at work etc.
The plastic clips holding the regulator bracket to the window seem to degrade over about 5 years. Then you will hear clicking. Or the cable runs out of lube and wears out.
The best place I have found to purchase as well has a lifetime warranty, I just send mine back and get a free replacement!
1aauto https://www.1aauto.com/
Hope that helps, search the forum for DIY window regulator and Youtube for tips. Get a magnetic socket set so you can hold the bolt that goes through the window as you are putting it on in a tight place.
Let me know if you have any questions. Good luck and save some cash DIY.