Help what can i do it won't even make any calls

[amy5966]

ok so for the past week or more i have been having troubles with my zio through cricket it doesn't seem to want me to make any calls or recieve and when it does let me it drops them. it has been showing a x where the bars are some of the times and others it will say 3G what do i do anyone else have any answers id take it to cricket again but everytime i do it magically works