I have had good luck with EKWB buying directly from them for example. When I had an issue with a pump they did RMA mine but instead they just send me a new pump. I kept the faulty one and now everything works great. EKWB is one of those company that I can say the level of customer service is just as good as EVGA level of customer service. Love both! So don't feel to worry but if you plan to try a few things and send stuff back I won't recommend it cost an arm and a leg to ship back to them or any company out there.
If you have to ship to them make sure you let them know your situation. If it cost as much as you buying a new item for the price of shipping tell them is not worth shipping it as you can buy a new one. Just be honest with them and communicate with them. Work with them if you have to run some test that they may require etc.... I did it for 2 weeks until they consider the item faulty. I provided images, report, stats etc... of all the test done and keep clean good communication with them.
Another option is
www.performance-pcs.com which is another company I do business with and they are great as well. No issues there on my end since I been doing water cooling for about almost year now.
Good Luck!