Amazon India — Moto g4 plus problem

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North Goa, Goa, 403503

Hi. I had ordered a moto g 4 plus ..order id[protected].. i hardly used the phone for a 20 days and it started giving problems ...like automatic restarting, no sound, no incoming outgoing voice unless i restart my phone...i contacted amazon but they said they cant do anythin and told to contact motorola...motorola said i need to contact service centre...
I visited service centre nearly 8 times for the same problem but they are not doing anythin...everytime they keep my phone for about 2to 3 weeks n say that it is repaired...but the problem still exist...what shoul i do...pls suggest ...or else pls exchange this phone...i hav hardly used my phone...around 4 to5 months it was with service centre