I have just started my family plan (four phones) on March 11, 2019. In other words, I activated four phones on March 11, 2019. When I checked the Verizon Bill, the billing period is Feb 11 to March 10 with the total charge of $327.xx. I have contacted the customer service about this issue. Someone in the customer service said it is an advanced charge, and he/she checked with the supervisor.

According to Verizon Q&A, "Verizon bills one month in advance, so your first statement will include partial charges for the current month, as well as charges for the following month. Monthly charges are prorated according to the number of days you are billed for during your 30-day billing cycle. When you make changes to your account following your service installation (by adding or deleting services or packages, for example) partial month charges will apply as well." 

My bill is not the advance charge. It is not prorated. Verizon charged the incorrect period because I never used their service from Feb 11 to March 10. I activated my phones on March 11, 2019. Do you have any idea how to fix this problem? They admitted the system error but not going to fix it.