I assume you mean a Fairphone 2 (the name FAIRPHONE is written at the bottom of the display)? What you describe sounds like the original “Regular Case” that Fairphone discontinued after just 1-2 years because these case kept doing what yours does. You can order a two-part “Slim Case” instead that will fit your FP2 just as well, and the good news is that Fairphone is offering a Slim Case for just 1 Euro plus shipping until the end of 2021:
