It looks like ur sister been f***ed up by irresponsible mechanic.
Just do like what other forumers say, refer to the proton SC and try sweet talk them to still allow warranty.
And please please please ask her to learn from mistake or just stick to LRT.
I'm using FLX as well and about the same age as ur sister's.It havent give me any problem and I enjoyed driving it.Reading how irresponsible she treat her car makes me feel heart ache already... .zzz