Surely there is a phone number, email address, street address or something on the bill you received?
I received a letter from them recently wanting me to email on a paypal receipt before they released my goods - I was not over the 22 euro limit so I was not liable for any charges but the email address was: dmc@revenue.ie
and I had to quote the parcel number they had assigned to it.
The VAT and charges are on the full cost of the goods and the postage combined, not just the goods as you might expect.
Unfortunately that amount sounds about right.