I would file a dispute only as a last resort. Disputing a charge with a rental car company has been known to put people on the Do Not Rent list.

I would wait for Budget ATL to call back (or call them if they don't call back). Escalate with a manager as necessary.

Failing that, I would reach out to a higher-level executive at Budget (some contact information is here). Include both your hand-written return document plus a screenshot from your credit card statement.

Only if that fails would I dispute the charge.