Just to make this clear:
* We're still without internet.
* We found the reason.
To make a long story short: first we tried getting internet through Clix, but they wouldn't pick up the phone, then we tried with Oni, and even signed the contracts, but they wouldn't manage to make our connection work, then we canceled with Oni and tried with Sapo, but meanwhile Oni made things happen and with Oni we stayed...
The fax we once sent to Oni, to cancel the then non-existing connection, has kicked in, months after we sent it.
It's now about two months we don't have internet at home and, quite frankly, we don't really care anymore.