Audiovox CDM8910 Issues

I have an audiovox CDM8910, without a sim card. I have Cricket service which does not require a sim card. Sometimes it will say I have full signal, yet I cannot send nor recieve texts, calls, or voicemails. There is no pattern to when it works and when it doesnt. But it normaly only works for a time period of 10 minutes, then it goes back to not working. No one else with this service is having these issues. The batterie is constantly dying, even if it was charging for hours. It worked fine when I first got it, but about a month into it this happened. I bought a new battery thinking that could be it, and that batterie actually NEVER works. Sometimes the phone will not work for days. It constantly cuts my calls, and never stays charged. It would normaly say "Charging is Complete" when it is, but if it ever does say that anymore its normaly once every week or two. The error messages it displays when the texts fail are either "SMS Connection Fail" or something along the lines of general failure (sorry I cant remember that one exactly). But its very frustrating, and has left me in quite the situations. If anyone can help that would be great.