Planet Fitness refusal to refund money that does not belong to them.

I am quite disappointed at Planetfitness on how they are handling my refund. I mistakenly made a double payment on 30 May 2024 and upon realizing this, I contacted their call centre to request a refund. They have been taking me from pillar to post about money that does not belong to them, promising to refund me within 72 hours. I am typically not the type to complain, however, the level of unprofessionalism when it comes to handling complaints is quite disappointing. I need my money back.