NEW PHONE

i have just upgraded me old Samsung S4 to a new LG G4. within a day or two i noticed i was not getting all incoming calls. i called vodacom and lg a number of times but no-one relly new what was happening. afte about 2 weeks of frustraation i sent the phone to Vodaworld repairs ( repai number***5) where after about 10 days they replaced the PC board but i got the same casing back. the result is the phone is exactly as it was before - not working. when i put my sim in my old phone i have no problems. the new one intermittenly stops working. i have been advised on numerous settings but nothing works. i have today sent the phone back to Vodaworld repairs. i would like a new phone. i am paying a subscription which includes the cost of a handset but Vodacom have the handset for longer than i do. i want a credit on my account.