Zingo s****** x200....unhappy customers

I bought a zingo x200 s****** for my son 2016 ...s****** gave me problems within 7 days it was bought .....took it back to game and it was send to tevo for repair and it come back ......it was ok for a month and it was send back for repairs as it was under guarantee..... to cut the long story short from 2016 august until today the s****** was booked to tevo more that 13 times...its always suffering from same problems ..the guarantee has lapsed and I had to pay 800 for it to be fixed but im still experiencing same booking in and back problem....I spoke to the tevo managers but seemslike they dont want to assist me .... My child has never enjoyed the pleasure of owning a zingo s****** as it's always booked in for repairs ....I have all receipt to prove that the bike has been having fault from day 1 . .... Jeanet in tevo centurion and her boss are failing me as a client and now I need to know what else can I do .....the s****** is with them as we speak for 5th time in 2018 for repairs.....I only need a new s****** from them and admitt that the s****** has factory fault. Pls help