This may require removing the seat and disassembly/reassembly or replacement of the seat track system. Not sure of the construction, but there may be a roll-pin or rivet or other piece of securing hardware that has failed, allowing this rail to move rearward from it's normal location. Personally, I'd unbolt the seat tracks from the floor, remove the seat and compare the broken side to the still-intact side to determine the point of failure and replace with a suitable replacement, whether it be rivet, roll-pin or bolt/nut. I'm guessing it's long past warranty, so I would try that...what have you got to lose, except saving yourself a repair bill if you take it to a garage/dealership.