User Moparofficial not responding..
if i were in your shoes, i'd happily refund him if he rescinded the negative feedback and made a public apology.
if he isn't open to those terms, i'd still refund him, albeit begrudgingly. however i'd sleep well knowing that i have his address on file. it's shockingly easy and ridiculously cheap to have several yards of manure deposited in a driveway.