2004 Forester rotten rear subframe

Hello folks I am new here so please be patient as I need to learn the ins and outs, ta, my wife drives a 2004 forester, I can no longer drive due to eye condition, I'm kind of like the wee felt dugs that used to sit in the rear windows of cars, in a galaxy far far away. We have the 2liter non turbo all weather car, with 96,000 on the clock and it cost us £1550. A couple of days after purchasing it, the rear brake pipes failed, something else but I forget but anyway the mechanic says we might need a ( new one ?) rear subframe. Car is due its mot in January sometime. Any suggestion much appreciated, when I said " we" I meant the car as we are far too much gone for any help.