When a group of Sth African migrant teenagers go on a road trip they have an accident that leaves one the boys paralysed from the waist down but when the parents of the injured boy engage in a legal battle against the young driver it divides a community in a gripping saga of tradegy and triumph.

First, it is too long, and as said before it doesn’t hook a potential viewer in. It should be less than 30 words, and in my opinion, the whole first part could be cut as stated by CMathias and the suggestion there is good.(“When a road accident leaves their son paralyzed, the determined parents engage…”). Honestly, looking at it cutting the first and last parts out would probably do, you’re really just trying to explain too much. So: “When a road accident leaves their son paralyzed, the determined parents engage” in a legal battle against the young driver it divides a community.
But I think that there should be more emotion in that, so maybe mention that the parents are poor, or need the money if their son is ever going to walk again, otherwise it just seems like the parents are suing an inexperienced driver so they can get some money, which makes it harder to root for them. And make sure to state a clear protagonist, if it is the injured boy or the parents. And you possibly even antagonize the young driver, maybe saying that he’s a reckless rich kid who doesn’t care whom he hurts.
Anyway, aim for less than 30 words.