I have noticed today that the rear subframe mounting position I badly rusted where the rear subframe plate mounts any advise on replacing that area 

In the pic  the area around  where it should be is solid  also found filler in that area tut tut last owner 

Oh dear Jonathan, that doesn't look good! Is that the fuel tank it's right next to as well? An extra complication for any welding in that area, it'll likely have to come out. Perhaps call round any local welding specialists including mobile welders, for someone willing to take it on, this is clearly not a job for a main dealer 😉