Wrongfully Billed and refuse to reimburse!!!

We had a shipment come from Canada. We have been dealing with them for over 10 years. We use to deal with TNT but they were bought over by Fedex and we started using fedex. That's where everything started going wrong. Our shipments were not delivered because clearing invoices weren't being paid. But we weren't being SENT the invoices TO pay. All this I had to figure out and sort out. Now we have been charged duties on a shipment we are not suppose to!!!! I emailed a fedex representative to sort this out for us, her snotty reply is; I approved the clearing instructions and there's nothing she can do about it now. Are you kidding me!!!! Fedex incorrectly charged us duties when they were not suppose to, and now because us, the CLIENT didn't pick it up in time, now we must just pay it because there's nothing you can do to reverse the charges or credit us in some way?!?!!?!? Pathetic!!!! Fedex is sneakily charging you for things they not suppose to! Be aware people and use another courier agency if you can because this is actually a joke it's so ********. R8800 is not that much maybe. But if they are doing it to 120 people a month. It's a million rand. A million rand of OUR money they are *****ING!!!!