Rear Seat stuck down due to locked seat belt

My mother in law has a 2006 Saturn vue she uses to cart my kids around in. She put the rear seat down which now is stuck. The reason is the middle seat belt (built into seat) has locked and won’t release the tension.

As far as I can tell GM unlike Honda and Subaru does not offer a lifetime seat belt warranty!

Any one experience such a thing and able to correct?

Is the seat belt buckle fastened?

The seat belt is not fastened. When the seat goes down it retracts at the shoulder part. The problem is that will not go back out. I am hoping removing the entire seat is not the solution.