I am a UK resident and during a road-trip I made to Italy I (unknowingly) went to a restricted road which I was not allowed to go in. This apparently resulted in me being liable for a fine. However I was not actually aware of this when I did it since the system that flagged me was an automated camera based system. This apparently resulted in Italian authorities cooperating with UK authorities to track me down to send me the fine.
This apparently happened about a year ago and the Italian authorities ended up sending a tracked, signed for, letter containing the fine I was liable for. However I never received this letter. I became aware of this whole timeline when I was more recently contacted by a UK based collection agency which was employed by Italian authorities to collect the fine plus deadline increase and Late Payment Charges. This had made the fine significantly more than it was originally.
The agency sent me proof that the package was delivered and signed for. For context, in the UK the signature happens on a touchscreen and the mailman also fills in the name of the person who made the signature. In this particular case the signature was not mine and neither was the receipient's name, nor was it of any person I know or recognise (in fact it was just 3 letters, maybe initials, no idea who they belong to though). I informed the collection agency that since I was not made aware of the fine the first time around I should only be liable for the original fine, without any extra expenses or increases however this was their response to me:
[...] as far as we are concerned you received the original notice our client sent out to yourself.
This therefore means that whoever has signed for it on your behalf has made you liable for the deadline increase and also any Late Payment Charges our client have decided to add on the account.
Now I am not a lawyer nor do I claim to understand the nuances of the law, but this has struck me as very strange and hard to believe.
Therefore I am wondering if this is true, does signing for a letter that is not addressed to you make the person it is addressed to liable for its contents? Does this even apply if a letter is delivered to the wrong address by mistake? Is there any relevant precedent to support the collection agencies claim or are they making this claim in order to do whatever it takes to collect as much money as possible?