Motorola Solutions — motorola g4 plus not working properly

Dear sir/mam,
I have purchase new motorola g4 plus on 25/1/17, it was working properly for few days only but after that i faced enough problem in operation the mobile.
As i saw the functions were working automatically, and can't be stoppable.
Sometimes hard to answer the calls, everytime i switch off and switch on to make it work properly, also everytime if i want top operate if it in charging, i face again the same problem. I took it to service center on 2/9/17, they said it must be software problem, and they re-update the software, but its still the same.
I was also informed from service center techn. That this model of motorola has the problem and cant be solved.
I request from the motorola co. That if they cant solve the problem, they must change the set with other one or other option i must get from motorola company, if they fail do to this i will go higher complaint against them.