I think this is a bug. My case: I upgraded from the SM 2GB plan to the M 4GB plan in the middle of my cycle and chose to get the upgrade right away. Then a few days later I get an email saying that I only have x% left out of 2GB, which doesn't make sense because supposedly I upgraded to 4GB. I go to my account online and it says that the plan was effectively upgraded to 4GB, but under "my usage" it still says I've used so much out of 2GB. So I call support and I'm told that I didn't get the full 4GB because I did this in the middle of the month and that it was my mistake to choose the upgrade inmediatly if I wanted the 4GB right away... Now I get that because I had already used so of my data I was not going to get the full 4GB, but in both the email and my account it should said that I had so x% out of 4GB not out of 2GB. That is what is confusing and a bug!
The customer support person was kind enough to give me a temporary upgrade, but she missed the point that there is something wrong in the notifications and in the My Verizon UI.
By choosing to have the plan change by effective immediately, you basically asked to have your billing cycle split between two plan allowances.
You should have selected to BACKDATE the plan changes to the beginning of the current billing cycle. That way you will have access to the full 4 GB data allowance.
With the immediate change, if you have a 30 day billing cycle and you change the plan on the 15th day, the first half of billing cycles has only half of the 2 GB plan or 1 GB to use during that period. The second half of the billing cycle would have 2 GB of the 4 GB allowance. This is called having the plan prorated. If you had used 1.75 GB in the first half of the billing cycle, you will also be charged for the 0. 75 GB of overages in a 1 GB overage charge.
I'm most definitely NOT a VZW employee. If a post answered your question, please mark it as the answer.