most companies charge for the remainder of the month then add in Aug's bill. This is the norm . I would be curious to see why it turned out to be 107? Did you get a tab and what are you paying per month for your plan plus the tab? Then add in the remainder of July. If something still seems off, I would give them a call.
plan (July 20th - 31st, and Aug) plus tab plus tax.....
so it does sound like Aug with your tab plus July 20th and half the tab for the month plus tax. Sept it should be 65 + 8 + tax.
Like I said most companies do this. They charge part of the month from when you start using their services then charge you Aug because you're into Aug at that point.
Maybe the sales rep should've explained that part of the tab gets charged as well which brings it up to 93 plus tax which brings it up around 107 a bit better.
I have a feeling he may have said 90 and most of the time its usually before tax.
You do know these plans are before tax?
This is a one calculation if your billing cycle is from 29th of the month to 28th:
You bought your phone and plan on the 20th.
Then your first bill included partial charge of service and tab from 20th to 28th(9days) + one month full
$65 plan / 30days x 9 days = $19.5 - partial charge for your plan
$8 tab / 30days x 9 days = $2.34 - partial charge for tab
$19.5 + $2.34 + $65(full plan) + $8(full tab)= $94.84 + tax(if its 13%) = $107.17