Sending and receiving packages in Italy

Sending parcels and packets via the post office is a simple and easy process and for within Italy they have a cheap 'paper' only (magazines, books and newspapers usually for students) offer and for large items up to 10kg there is a 'Pacco slow service' that is also very reasonable. It is possible to book this service online, take the parcel to the post office and they handle the rest.
This site is also useful especially if like ours the post office only opens certain days of the week:  http://www.parcelscout.com/index.html
To send packages within or out of Italy we have found the best comparison site to be: https://www.spedirecomodo.it/Data.htm
We have used the cheapest uninsured service twice to send large boxes (40x40x30cm x 10kg for 21.50 euros) to the UK and they have arrived, tracked all the way, at their destination without incident.

Receiving packages and parcels is another story. Recently we ordered from Amazon.it and the package was to be delivered by GLS, it never arrived after a catalogue of lies i.e wrong address on the package, no-one home, wrong telephone number etc, despite sending GPS coordinates, directions, a Google map, the driver eventually said we were out of the delivery area despite having received packages from them in the past,  the parcel was sent to Milan and it was suggested we collect it from there despite us living in the Perugia area. As Milan is a 10 hour round trip they were told no and Amazon refunded our money. We are not alone as many people we have spoken to have the same issues with this particular company.
BRT (now a subsidiary of DPD/ Interlink), DHL, Fed-ex are all on the ball and we've had little or no issues with them. SDA (part of the postal service) is either super efficient or you have to track the package down to your local office depending on the driver we think.
Look at Trustpilot for views from Italians and ex-pats on the various services, its an eye-opener.

I've used Fedex, DHL, TNT with no problems at all for either home delivery and pickup or in receiving parcels. I have sent and received parcels from the UK with no problems as well as receiving parcels from Germany and Austria with no issues. A good service provider for the UK (they also serve other markets globally such as Asia) is Intercargo.com. I was impressed with their prices and their customer service. DHL is also good. While sending a package Poste Italiana is also not bad but I would recc them for documents and smaller items. The other service providers referred to above I have used for electronic items such as laptops, books, chargers etc.

I'm using mailbox's to send my suitcase over, it's not cheap £70 but cheaper than a flight. I don't know if it will arrive but mailbox use internal courier services direct from one shop to another internationally so I'm assuming it's a great service!

My sister recently sent my a small package with some small bites per say. However, when I tracked it down there is this status "Segnalati problemi durante la verifica doganale per fattura mancante
Centro Scambi Internazionale Milano Gateway Poste Italiane" which states that there is no invoice provided when it was mailed through the post office. My cousin sent me a small package previously and there was no issue. Why do you think that is can anyone help? Both packages came from America.