Why is my Vauxhall Grandland's Automatic Transmission Not Shifting Gears?

I noticed that my Vauxhall Grandland's automatic transmission is not shifting gears properly. It feels like the car is stuck in one gear and I'm unable to accelerate or gain speed. What could be causing this issue and what steps should I take to fix it?

This issue could be caused by a faulty transmission fluid or a damaged solenoid valve. It's important to take your car to a certified mechanic for a proper diagnosis and repair.

There could be an issue with the transmission control module or the gear selector mechanism. I recommend taking your car to a mechanic as soon as possible to prevent further damage.

It's possible that there's an electrical issue with the transmission or the car's computer system. I recommend taking your Vauxhall Grandland to a dealership for a thorough inspection and potential software update.