You can't report buyers for making offers.
There are a few, very limited, specific reasons for reporting buyers and 'making offers but not responding to a counter-offer' is not one.
You could list the items without the 'make an offer' option.
Just list them for the price you want.
You can't avoid buyers claiming undelivered, unless you send everything tracked or 'signed for' - these claims do seem to be frequent from buyers of all sorts of cards.
You don't know that the card didn't arrive creased and dealing with 'not as described' claims is a part of selling on this site.
"There are two ways to be fooled. One is to believe what isn't true; the other is to refuse to believe what is true.”
Søren Kierkegaard, Danish philosopher (1813 - 1855)