First off, never install parts you want a refund or replacment on. No shipping company will honor insurance once you use the part. Expecting Coz to front the cost of the part after you void the shipping insurance policy is borderline insanity. This is common sense (maybe not for you..) and how every company dealing with drop shipping works.
Second, Coz will always work with you on an issue. Granted I've never tried cussing at him first, but over the hundreds of parts I've ordered from him I've never had one problem.