Any way to send messages?

Read the FAQ and wait.

Wait another 3 days before reporting.
There's no other way to contact him unless you find him in the forum and replies to him, or comments in the giveaway, wich he might not see, or would perhaps ignore.

You could create a group and name it whatever you'd like (a short message to the person) and then invite them to the group.That's the only way to communicate with someone who won't accept your friend request.

As Oxol said, you should wait three days and then simply report them. If he doesn't want to send it, there no one who can force him to.

if there was a way to PM people, that would be awesome :)

Steamgifts etiquette suggess that you should send a mail pigeon. If you still do not receive any answer in 3 days, than sending the assassin's squad will be the appropriate move.

7 days! You have 7 days before I kill you! HAHAHAHhahahahahaahha!