Sounds like by letting him hold that credit charge open you have allowed him to demand unlimited work for $800.
Have him run the plate for the rest of the sofa charge, pay the $800 and bill him for the work you have done so far—and from now on you should work to a contract you both sign.
If you have not had a contractual agreement thus far, remedy the situation.
Did you negotiate in advance how many rough designs you would present?
Did he select one and you made it using his copy and images—or if your text and/or images, was it accepted?
Usually a flat-fee contract included a specified number of rounds of revisions, and after that “AAs” cost. AAs are author alterations, and the non-stop revisionist client is reined in this way. [Your mistakes, of course, are no charge]; or you can have an hourly rate contract. With this you must itemize hours spent.
AND, if you feel that this job is taking you longer than it would take someone else whose skills weren’t rusty, take that into account. Estimate 75–80% of the hours it would take you to actually do the job [to keep your rate professionally respectable without being exorbitant] or if you do it on an hourly basis, knock off about the same percentage of hours when you write up a time sheet.
Be fair. Acknowledge your limitations [to yourself] but don’t let yourself be held hostage by an $800 credit card bill.