Can a buyer revise a positive to a negative on EBay?

DoNotInsertIntoMouth · 2013-11-01T22:43:17.000Z

Have a buyer who left positive feedback then had a problem. I am resolving it, but they are being somewhat unreasonable and I am considering blocking them after this. They have purchased from my store for a while, but not giving me any benefit of the doubt in terms of the problem and think they are entitled to big discounts because they keep buying from me. However, don't want them to be able to go back and revise like 6 feedbacks and ruin my score. Lol. Any ideas?