i have read many but i will share my own.
last month i ordered a "carbon reamer". it's used to round holes while blowing glass. when the reamer arrived the tip was broken. i took pics of it and immediately emailed the company with pics of the damage. that evening i got a reply, "we have sent you a new reamer. thank you for the email and the pics." they asked that i send the broken one back and they credited my account for the shipping charges. my new reamer arrived a few days later.
i bought a 250 watt MH ballast and bulb set-up from HTG. first thing i notice is half the screws holding it together are loose. i plug it in, it works for a few minutes then fails. then i try again, now the bulb just flickers. i go buy a new bulb at the hydro store. it works for 3 days then does the same thing. i emailed HTG the first time it happened and sent pics of the bulb. no response. i email HTG again. NO response. i emailed them at least 4 times and NEVER heard another word. i was told i HAVE to call him. BS, he took my money via email he can answer me via email. i am still waiting for a reply. it's been almost 2 years now.