They aren't come to you just for learning pure academic topics but else, in the past the students not just transferred academic knowledge but also moral, behavioral skill and the live outlook they learn how to live a life.
If they aren't being able to write that's a dangerous problem need to mitigate nonetheless, if they are lieing its same issue also need to handle.
Please work on that and give them other chance and please work hard on them, and remember the good teachers who's left a beautiful positive fingerprint on their students live eternal life through generations.
So be happy... And fix it... Smoothly