Samsung note 10

I have a samsung note 10+ it was sent in for repairs of the screen when the technician opened the phone they found that the motherboard was damaged too they then replaced everything inside the phone with the screen etc everything exept the cameras whas replaced so basicly i have a new refurbished phone but since the replacement of the phones intestants i cant make calls or recieve calls because the singnal keeps dropping or just simply does not get signal when i insert my sim card in another phone it work well,the phone has been taken back to the repair technician who then send it back to samsung in johannesburg according to them it works fine but when i get it it has the same isssue its been send back 5 times already with the same issue... it simple samsung this is your product which i am paying R1800.00 for every month so just replace the phone..