faulty handset

my son has a samsung galaxy s5 mini. the handset has been problematic from the day he took delivery of the handset.<br> the handset has been returned to vodacom, russel street branch, Nelspruit on 8 occasions.<br> the handset has been replaced and the new handset is still giving the same problems. no connectivity, dropping of calls, rebooting unexpectedly... to name a few of the problems. <br> the branch has not been helpful in resolving this issue.<br> i am sick and tired of excuses and bad customer service.