Don't deliver on your promise

On the 23 June 2015 I took my are in for a service. I explicitly told them that I am in the process of selling the car and I needed the rear seat belt fixed. On collecting the car it was not fixed as they said that the part was not available in SA, but if I paid a 50% deposit they would order one and it would take 4 week. <br> <br> Well it is now almost 8 week and the part is still not here and no one can give me an explanation why. It is very frustrating as I have to do all the chasing. The new owner is now riding around with kids that are not able to be strapped in the back . How is that for road safety