Anybody have trouble with verizon?

My son ex girlfriend stole his phone and we are with Verizon phone company. Phone has been on for almost 4 months now. He is on the same line with someone else. The billing passcode has been somehow changed. The account is completely locked. We walked into Verizon showing id's and basically for 4 months they told us its best to get another phone as the solution when we first spoke with a Verizon rep in the store. They told us they don't track phones so a police report is useless to have. His voicemail is still full and there have been people telling me they receive drug messages and messages saying my son is dead. We have been calling Verizon for a while now and all of a sudden yesterday they want a fraud report so they can shut the phone off. Have no payment been made since October. My son showed his id but the rep said the information did not match their records. We called the phone and the message was saying it was disconnected. Now the next day it was ringing still saying the voicemail is full. He can't even check emails or voicemail. They all have been hacked by her. what can I do about this? Verizon has let the phone stayed on all this time but refused the police report all this time until yesterday. They refused to shut it off. We tried to login to myverizon it still states the account is locked.