It sounds like the IMEI numbers have not installed correctly on your handset. The IMEI is a unique number that links to your phone. You can find your IMEI numbers printed on the sticker on the box your Fairphone came in. There are 2 IMEI numbers, one for each SIM slot
There is a fairly straightforward way of correcting these as the Fairphone is rooted, however it is a technical guide so I would suggest having a read through and seeing if you are comfortable doing… if not, you will need to contact Fairphone Support directly as I think they would need the phone back to correct this for you.