Did the kit include a water pump?

Make sure you have not driven the car for more than couple of seconds when temp gauge was in the red zone.

The vehicle must be turned off if the needle rises above normal operating temperature, otherwise there could be damage to the heads or headgaskets, although it is rare, it is not uncommon.

Also bring back to the workshop and ask them to do a pressure test on the cooling system. Make sure that there is water is the cooling system first. Do not open the reservoir filler cap when hot. Fill it up when the car has cooled down.

If unsure, get someone knowledgeable to look at it.

GL.