Are credit card companies loan sharks?

I have to tell you, with a few credit card companies that we have had, I am thinking more and more that they are loan sharks in disguise!  Recently my hubby and I paid off a card.  We received a statement, paid the balance in full well before the due date and we thought that was the end of that!  We were mistaken to say the least.  I was quite shocked when we received a statement two months later.  Mind you I didn’t get a statement to make a payment during the month of August, but did just receive one for a payment due in September.  My hubby called them on the phone and they explained to my husband that the payment was held until it cleared so it didn’t officially “post” to our account until two days after a due date so there was a late fee assessment.  Add that to interest and it was $89.00.  No flipping way.  I called them back as I looked at the statement and the late fee was not “disclosed”.  It was all listed under “interest”.  I demanded to speak to a supervisor and they did take off the late fee.  They said the interest is continued to be added “daily”, even if we pay the balance in full from the statement.  I said if this is the case, we will NEVER be out from under you.  You will continue to charge me interest even if i paid, they still send me another invoice for a few dollars, then what another one for 50 cents!  Horrible Horrible Horrible!  How greedy can they get?  You pay the entire balance and its not enough???  It’s like taking a loan with a loan shark!