cellular

hello, i bought my phone in March for few days now im facing the problem that my phone is not working well, what i mean is, my data and connection are on and off like every 5 minutes, but if iconnect to wi fi its completely fine, i tought that problem with my simcard and data but i tried this sim card on other phone and it works well, so i went to the icare center what they said me to do is to do factory reset! i dont wanna do this, why should i? I bought my old phone 4 years ago and its still working fine never done FR before