Then why did FedEx explicitly told me that the 50EUR was the charge for the paper to pick it up and not for the package itself ? Why did the customs told me that there was no charge for books and that anyone with the paper for the package could pick it up free of charge ?
By FedEx i mean "Rangel Expresso SA" (www.rangel.pt or www.fedex.com/pt) which is their representation (Global Service Participant (GSP)) here in Portugal.
By customs i mean airport customs (the ones i contacted), not the portuguese state customs. I don't know how they evaluated the package, they probably didn't even knew about it (due to lack of staff or other stuff...).