Got charged for going over in Texts even though I only used 3000/5000

Question

At the end of last month, I started texting a lot more than normal.  Knowing that I had the 500 text plan I figured it would be a good idea to bump it up to the 5000 text plan on 7/31 figuring that they would just charge the extra $10 to my bill and I would be OK since when I got this phone the sales lady said that if I noticed that I was going to exceed the limit I could just change to the higher plans whenever I want.
Turns out that while I can switch to the new plan, instead of charging me $10 more they refunded me $2.90, from the 500 text plan, and charged me $5.80 for the new plan at a Pro-rated price.  Normally this would be OK but when I looked at the bill it went from normally $90-100 for the 700 Family Share Plan with 500 texts on the main line and an extra line to around $225.  They had, by Pro-rating both the return and the new plan, caused me to go over in texts adding an additional $91 to my account.
Since they Pro-rated the 500 text plan via the return and still applied that texting limit through 7/30 I was given 371 texts for that period which I ended up using 623, going over by 252 charging me $25.20. Also with the pro-rated 5000 text plan I was given 1452 used 2110 going over by 658 charging me $65.80 for a total of $91 in charges that should have been $10 for the upgrade for the entire month from 500 to 5000 texts.
I have emailed Verizon and in a few minutes I am planning on calling and filing a complaint to try and get this rectified, any ideas would be helpful.

Answer 1

In the future, either change your plan on the date that your billing cycle begins or call into CS and ask them to either A) schedule the change for the first day of your billing cycle or B) backdate the plan to the start of the current billing cycle.  Those are the only methods to avoid pro-rated charges.  If you complain, Verizon may refund up to 50% of the overages you incurred, but since you made the plan change without asking for backdating, you agreed to the pro-rating.  There's really not a whole lot Verizon is going to do for you.