A trip to your local transmission specialist is the first step here, and don’t even think about driving the vehicle father than that. You could easily do more damage than is already existing. Modern automatic transmissions are incredibly complex things and there’s a lot that can go wrong.

You might be lucky and simply have a low transmission fluid level (although you’ll still need to find and fix the cause of the leak). But, equally, you may have a transmission that is literally on its last legs. The problem is that all these symptoms can show up through all sorts of transmission woes.

Either way, a specialist workshop should be able to diagnose the problem and work from there.

Modern vehicles have lots of electronics that operate functions such as the dashboard and warning lights. If the car is showing a 4WD light when it's not actually in 4WD, then there's an electrical glitch somewhere in the system.

But the fact that it occurs in tandem with a second fault (the incorrect speedo reading) makes us wonder if you're not looking at something as fundamental as a bad earth somewhere on the car. Electricity can't flow if the circuit isn't earthed, and this is a common source of problems like the one you're seeing. A good auto electrician should be able to sort both problems with simple test gear. If not, a scan of the vehicle's systems may throw up the answer.

Your owner's manual should give you a bit of insight here, but often, functions such as these can be turned on and off via menus within the car's infotainment system or its switchgear.

What's probably happened is that the car's battery has been disconnected at some point during the servicing procedure and the car has reverted to what's known as factory settings. If there's no provision for turning the warning buzzer back on, I'd take it back to the servicing workshop, as something has been altered to disable the buzzer.