Toyota Estima 2003 transmission problem

Hi, can someone please suggest me what to do?

Our Toyota Estima doesnt want do shift after 50 minutes of driving. Looks like in third gear it doesnt want to shift down to the hill. We had to let the char check with automechanic and change oil with filter. Gearbox specialist told us straight away to change gearbox what is almost price of your car. We are in Cromwell, New Zealand. Here are some specs of our car:

2.4 Litre Petrol, 4 Cylinders, 4WD
X limited 8ST, Silver Station wagon
4 Speed Automatic, Rear Wheel Drive, 119kw
Fuel Type: Petrol, CC rating: 2,360cc

Thank you

Impossible to say.

The only things you can check are the ATF level and condition..if those are ok then it maybe your box has failed...what mileage has the vehicle done.?....generally these boxes are pretty long lived.

Do you trust your gearbox "specialist".?

Are there any codes in the gearbox ecu, does it do it in 2wd, 4wd or both, have you checked the fluid in the transfer case