you can either swear or put donw their address

in either case that sort of feedback tends to get removed fairly quickly

or you can ask someone to construct a well worded not sweary reply to put up for all to see

along the lines of:

complete and utter scam artist conned me good and proper

or:

you dirty cunt, wait till i get my hands on you

or:

give me my money or i'll burn down your house

alternativly you could put:

soon to be convicted sex offender, read the paper

and then write to the local paper and get the local goon squad out to beat him up