Cell phone not taking the password to unlock

A sumsung galaxy S4 mini not taking the password to unlock the screen and the password was never changed and was the same always. The problem that I have is that it sometimes open and sometimes not after trying several times to open the phone. I have tried to contact the call centre to assist in changing the password to be disabled because is giving me problem but this was in vain. I have been told to go to my network company to reset the password and this is going to cost me because all the date that is saved on the phone is going to be lost.<br> I have never heard of a situation like this, this is really a bad product for me.