OT bank notification of debit card use, continued

First, is there a newsgroup that specializes in banking, or commerce,
or business, or anything for which this would be on-topic? And
where people might know the answer to what I think is a very strange
question?

Some of you may remember that I get notifications from the bank every
time my charge card is used a) to charge more than some amount, maybe
$100, or b) to buy something outside the 50 states.

And you may remember my complaining about being charged $110 for a car
that only holds 10 gallons of gasoline, when every other gas station
charged between 50 and 57. Did I mention that the overcharge
happened twice, 110.19 and 109.74.

So today I went to the gas station and showed him a copy of the email
the bank sent me, and said, What do you think abouty that? We dont'
speak each other's language but he knows a little English and he said
"You didn't pay that". I assumed he was referring to the foreign
exchange commission, and I pointed out that no other gas station had
charged more than 57. He also got the guy who works behind the
counter, whose English was pretty good, and all he did was say the
same thing and give me the gas station chain's phone number.

But by the time I got back, it was after 5, so I called the bank in
the US.

(BTW, it used to be very hard to call an 800 number in the US, but
with Skype you can call it like any other number. You still pay the
2.3 cents a minute for Skype, but you'd have to do that anyhow and you
don't have to convert 800 to 8nn like you used to, (and in years
before that, you had to find their non-800 number) .

So the girl at the bank, who seemed a little flighty, told me that on
April 3, I hadn't paid $110.19, only $44.76, and on
April 10, I hadn't paid $109.74, only $34.36. Plus in each case
about 1.30 transaction fee.

I didnt' believe that, but I looked at the online monthly statement,
and by golly it was true. What's going on? Why are they sending me
emails saying I paid much more money than I did?

And what is the relationship?. The first one is 2.46 times the real
charge, but the second is 3.19 times the real charge!!

Now I have to go look at all the other gas station emails and compare
them with the monthly statement , and with the receipt fromn the gas
station.

For that matter, there are all the non-gas purchases I should compare,
restaurants, grocery stores, museums, and outdoor stuff like zoos.

The rentacar company keeps pinging my debit card account. For the 3rd
time they pinged it for $2400 but so far I think they've only billed
me for $650. I understand why they checked int he first place, and
maybe they put a hold on 2400 but the hold only lasts for a month?????

But the rentacar company doesn't know how long I'll keep the car or
how much damage I will do to it. The 800 extra is the maximum I have
to pay if I damage it (though I was told 550, so there may be a
fight.) But the gas station knows what the bill is 5 minutes after I
start pumping. Why not check or even put on a hold for the largest
tank any car has and then charge the actual amount 5 minutes later.