Yes, I have made up my mind why this backlog increased this way:
As for the second part of your post, I feel like you’re asking me in a criticizing way, but I don’t seem to get what you’re actually criticizing.
I am not saying that Fairphone is falsifying their numbes, if that is what you mean. But at the same time, just because somebody has a problem with his phone and opens a support ticket, doesn’t mean he’s giving the phone back. So neither is a support request reducing the number of sold phones.
I actually do believe that very few people are really that unhappy with their phone that they return it. At least, there are very few in the forum who are writing to do so. And I guess the forum is the first place people go to ask for help.
Since only Fairphone can read the support tickets, hence only they know the variety of the problems reported in these tickets, we as a community can only go by what we read in the forum.
Either way, I am not able to say, how many devices are sent back for repair, nor how long it takes to repair a device, because I guess this is very much dependent on the very problem and how quickly its origin can be found. All I can tell by the backlog history is that from time the first FP2s were shipped (end of 2015), the backlog started to grow noticeably.
I might of course be absolutely mistaken. Maybe the majority of tickets is come from some FP1(U) problems which occured in the same time period. But I find that rather unlikely compared to my former assumption.
Companies like Apple or Samsung would probably not do a lot of investigation, but rather just make a backup of the sent in phone, flash the backup to a new identical device and send that one back to you. But I guess that’s neither the philosophy of Fairphone, nor in their budget.