Hope this helps. Nick.
The washer/dryer should have been clearly stated in writing on the purchase agreement or clarified on an addendum.
...but really, is your seller that poor that they "need" used appliances? Seriously?
Each party needs to go back to their sand box for a time out, and evaluate an hourly rate to fight for used appliances and come to an amiable solution. In the meantime, the agent needs to avoid huffing and puffing to make a sale...gives the rest of us a bad name.