All the blue and orange taxis have a telephone number to call on the windscreen to report them if there are causes for complaint and their license number. Especially if they don't use their meters or cover up the meter with the fury dashboard cover
But using the meter to El Gouna doesn't give them much so I would pay LE50 as there is no guarantee of a return fare.
The same in El Gouna. If the taxi is from El Gouna limousine threaten to report them if they try tricks like this. A few years ago I organised a taxi to take tourists to the airport from El Gouna. He stopped half way along the back desert road and demanded twice the price. Just get your mobile out and tell him you are calling the tourist police.