Let's start with Garanti Bank. I bank with Garanti because my salary is directly deposited to the bank. After receiving my new credit card, I had some questions about the card so I called the bank. In the US, when you call a company to speak with a customer service rep, you almost always hear an option for Spanish speakers. Well in Turkey, it's the same think except the option isn't for Spanish, it's for English. The English speakers with Garanti are very helpful and their English is clear and easily understandable. While they aren't always the most knowledgeable staffers, I can easily communicate with them.
TTNET, my ISP, also does not have an English website. I did find their English speaking reps on the phone to be helpful. I once had a technical issue that required follow-up with their technical service department. I was informed that I would be contacted shortly by an English speaking tech. Sure enough, someone called within an hour and helped me with my problem.
Vodafone in huge in Europe and many countries around the world. According to Wikipedia, they are the second largest mobile telecommunication companies in the world. Unfortunately, they too, do not have a website in English for residents of Turkey. Luckily, like the other companies I've talked about, they have pretty good English speaking call center staff. While the English speaker from Vodafone was the most difficult communication I experienced, I was able to call and get answers to my questions. They helped me out.
I'm sure there are many other companies in Turkey that offer English speaking services to English speaking residents in Turkey. I've found that most governmental agencies do not have English services. Luckily, my Turkish wife is by my side to help me when I'm in a bind.