Bad experience with BMW Sa

I bought a 4:30i two years ago and it has been having issues with overheating and has been getting fixed but every time I travel long distances in the vehicle the problem keeps persisting and have reported the problem to BMW SA but my problem has not attended to thoroughly. For the fifth time it has overheated but this time in town and I’ve had to abandon it and walk as it has completely shut down and won’t even start . It’s still on motorplan but my experience with the car is so bad as i hav been stranded on numerous occasions in this vehicle. I am so disappointed as I am paying large amounts of money monthly for a supposedly luxurious vehicle but all I hav received from it is stress and hardship. BMW SA has taken this lightly and I am considering legal action to address my concerns