I changed my plan recently but I am aware that both of these plans have 500 local airtime call. But why am I billed $64???
Can you give more details looking in page 3 of your bill? It'll explain it all there. But if you went from one not unlimited talk plan to another, you'd have minutes pro rated to the number of days you had each plan. So 500 at 15 days would give you 250 minutes. If this time period you used 300, you'd be charged To minute overage.