Global data roaming and time change

[AC Question]

Phone will change time zones. Tells ugs that it's global data roaming. When it's in a different time if we send a txt message it will not send that message until the time the phones says it is. Connection to service poor; if any only works if connected to wifi. Dropped calls. Battery drops charge quickly even when in airplane mode. Been to store (80 miles from us) several times and some worth people in Tec and customer service. Have tried changing SIM cards and had another phone sent to us. Nothing has fixed the issue