I have some problem in rear chassis

I have purchased xuv 300 in month of March 2019 I have some issues from purchase date of car the car had major issue in rear side its rear chassis nut bolts loosed every time I have 6-7 times visit to workshop or mechanic same problem s occur at the time mechanic said that it has 14 no bolt rather it to be 17 no. Please solve this problem ??