Whirlpool american fridge freezer model s20brsb21a/g leaking

I have a whirlpool American Fridge freezer model number 858615115000, it is 12 years old and water has started to leak from the front right of the fridge compartment under the door. I have checked under the freezer compartment at the small drip /water collection tray and this is empty. I have also cleaned all the fluff from under the front of the fridge (it was alot) so that the fans can work to evaporate the water underneath. But again the tray underneath is empty. There is now a continuous stream of water coming from under the fridge its soaking up two towels per day. I am wondering what else it could be, is it worth repairing or is it likely to be an expensive repair. Help and advice urgently required please