Ford - I had several and they all had some issue which was impossible to resolve and the garages lied about having fixed them.
Vauxhall because one failed on me and the garage stonewalled me.
Tech21/SansAmp and Panda Future Impact - there was an incompatibiity between their kit and they both said both tough.
Brighton - the council pursued me over a parking fine despite acknowledging that I had a valid ticket; fortunately they messed up their procedures and had to accept failure, however their dishonesty was not to my liking so I steer clear of the place.
My local Tory MP - I wrote regarding a parking issue at a shopping centre and he replied saying not his problem. I also wrote to my local Tory counciller and he responded similarly; when he knocked on my door coming up to the local elections I told him I wasn't voting for him and why, he lost his seat. Plus I don't go to that shopping centre anymore.
Most soft drinks companies, because I disike the taste of artificial/substitute sweeteners, so there's no point in buying their products. As it stands, there's only Coke Original, Fever Tree, and some Romanian ones left for me to buy. On the plus side my meals out are usually cheaper, because I only have tap water to drink.