Unfortunately this is probably best taken to scrap metal for best price available.
Not many will repair a gearbox in these cars.
It is terrible they were allowed to sell these flawed cars or not be forced to buy them all back.
Cash in rego, get best scrap dealer price and do it asap to recouped rego.
Sadly you have a high mileage car with terminal issues.
Credit to the service regime it lasted so long!