GearboxNeedsReplacing

Hi guys. I have an A4 2011 2.0 TDI with a gearbox that has more or less disintegrated and needs to be replaced. The car has 108k miles on it and has been serviced from the Audi dealership regularly. This car is my first car and I really want to keep it for just a little longer but the dealership has quoted me £12k to get a replacement gearbox. Do you think its worth it to get this into an independent garage and fixed for something around £3-4k?