[Resolved]  Fedex — Tax bill a month late, now collection agency wants me to pay

I received a bill without any description (invoice number:[protected] half a month after the payment was due. The payment was due 1st of Dec, the bill was received the 14th of Dec. Also, the bill said that this was a reminder, while no other bill had been received before.

I would have paid immediately if I got a description of what the bill was for. However, I only received a billing amount and account number to send it to. I think anyone who has heard of scams would think twice before paying a sketchy unclear bill without description, so I sent an email asking for a description of the mail. After a few standardized emails that did not answer my question, I received the description of the bill. I paid the bill once I received the description and saw that it was actually a bill regarding import taxes.

In the mean time, so much time had gone over that they had now hired a collection agency to collect this money from me and they now want me to pay four times the initial amount (which was already more than half of the price of the package that the tax had to be payed over).
Now I have sent over four emails asking why I should pay the collection agency when they could not give me the bill 1) In time and 2) with any description. They keep answering with other details, none answering my actual question and when I call, they refer me back to the website's FAQ (where my question is obviously not answered).