Nextdoor Charged Me for an Ad I Canceled and Refuses to Refund My $100

With a company like Nextdoor, I had never had such a frustrating encounter. I recently started an advertising campaign with them, and they charged me twice—once for $100, which was accurate, and then another $100 for an advertisement I never even placed. They returned the second $100 fee at last after several emails, but they still refuse to refund the $100 for an advertisement I canceled within hours. Under the three-day right to withdraw, I behaved within my rights. I have emailed several times to stop the charge, but either they ignore my pleas or respond generally. After almost two weeks, I have had more than ten useless email conversations. To fix this, I have now had to challenge this with my bank.