NHTSA Complaint #11223033 — 2008 LAND ROVER LR2

I PURCHASED THE CAR IN MARCH OF 2017 WITH 101,000 MILES ON IT. IT NOW HAS 119,000. AS OF 24 JUN 2019, THE REAR END BEGAN MAKING A NOISE WHILE TURNING. I TOOK IT TO A LOCAL IMPORT REPAIR SHOP. MY MECHANIC INFORMED ME THAT THE DIFFERENTIAL IS CURRENTLY BEING HELD TOGETHER WITH ZIP-TIES. ZIP. TIES. AS I HAVE NEVER HAD WORK DONE ON THE REAR END OF THE CAR, THAT MEANS THAT THE ZIP-TIES WERE PUT ON BEFORE I PURCHASED THE VEHICLE. I HAVE NO IDEA WHEN BUT THE REAL QUESTION IS THIS: HOW LONG IS A DIFFERENTIAL SUPPOSED TO LAST? THE DIFFERENTIAL IS CURRENTLY LOCKED INTO ALL-WHEEL DRIVE ALL THE TIME. THE DIFFERENTIAL ALONE WILL COST $4900. THE FLUIDS WILL COST $40. I AM NOT SURE ABOUT THE NUMBER OF HOURS OF LABOR BUT IT WON'T BE OVER A DAY. SO LET'S SAY A DAY OF LABOR WOULD BE 8 HRS AT A RATE OF $120/HOUR. 4900+40+960 = 5900. RIGHT NOW, MY VEHICLE IS ONLY WORTH 2,200. I OWE NO LOAN BUT I AM UPSIDE-DOWN NONETHELESS. THIS IS NOT WEAR AND TEAR. THIS DIFFERENTIAL WAS POORLY DESIGNED. THE POOR DESIGN WAS EXACERBATED WHEN THE DIFFERENTIAL WAS NOT DEALT WITH. IF NOT REPLACED, THE LOCKED DIFFERENTIAL WILL DESTROY THE TRANSMISSION. THEN WHAT WILL I DO?