I’ve been using my Fairphone 2 for about three months. So far the only issue I can remember has been that the soft and hard parts of the regular back cover started getting separated near the micro-USB port a little while ago. I e-mailed Fairphone about this with the appropriate subject line and pictures, and they answered the next day, saying that I can choose one of the regular back covers and they will ship it to me as a replacement, free of charge. The new back cover arrived very quickly, in only a couple of days and it’s been fine so far. I tried gluing the old back cover and will try to keep it as a spare. Overall I was very happy with the support.
I’m sorry that you’ve had such a tough time with your phone.