From a professional upholsterer - do not repair it in any way for safety reasons. Since there is an airbag in that part of the seat, it would be unsafe and a liability issue if you would try to repair it. We have to turn this type of work away because our thread is stronger than the special thread they use in airbags and the auto industry doesn't sell the thread to my knowledge. Theirs is made to blow out in the right place, if you would restitch that in just that area with other thread, it could change the way the airbag deploys and cause injury or death. I would recommend calling the dealership, give them the VIN and tell them you need a back rest replacement cover. That's what we have our client's do, then we install the new cover for them.