These are companies that I have not had a good relationship with. I include a brief description of why I am not satisfied with them.
Stirling Power. I have used Stirling for many years and I did consider them to be good. However in the last three years I have had cause to contact their technical department three times. In the past they were very helpful however my last three contacts were less than satisfactory. In fact, frankly, the person I spoke to and their e-mails were rude. They told me that I did not know what I was talking about. I then quoted my qualifications to them and after that received a slightly more sensible but very non committal response. I now use Driftgate but have also had good contact with Victron Energy when I needed technical help. It appears to me that these problems started once Stirling started having things manufactured in the far East.
Trojan Batteries. I purchased some of their deep cycle batteries while in Greece and read on their web site that they had a 7 year guarantee. When we collected the batteries in Athens Mo was assured three times by the agent that the guarantee was 7 years and that the receipt was all that was needed. It was not worth the paper it was written on. After just two years while we were in Spain one of the four batteries failed and we had an incredibly difficult job trying to obtain a replacement. I tried to contact the head office in the USA when I could get no response from the Europe agent. The Europe agent then sent a rather sarcastic email saying that I should deal with him. It took weeks and the threat that I was holding them responsible for anything that went wrong on our forthcoming Atlantic crossing with our electrics before the Spanish agent sent one replacement battery. From my experience it appears that Trojan's guarantees are no better than any other company.
Vetus. I have used some Vetus products over the years and as far as I can see the basic products seem to be reasonable quality. The problems I have found is that some spares are difficult to find and also the spares can be incredibly expensive. Also on my stern gland the flexible hose joining the stern tube to the packing gland is really stupidly designed. It is not a straight section of tube, it has different internal diameters at each end. While in Greece I tried to purchase spares and the prices were twice what they cost in the UK. When I complained to Vetus they simply said that the Greek supplier could charge whatever they liked. I now look for other suppliers of Vetus spares such as = http://www.abcstore.co.uk/default.asp
Whitlock Steering. Used to be a fairly good company but began to go downhill shortly before being taken over by Lewmar. I haven't used them for several years due to my last attempt being a disaster. They would not sell me what I wanted and after three months telephoned to say that the steering which I never ordered was ready. I had already received the parts I needed from Edson within two weeks. I notice on some of the forums that people are replacing their systems with other makes.