Stole R350 and badly trained staff

Two months ago I returned a Iphone charger to The Vodacom Walk In store (the charger was still in its original package-was not used). The staff indicated that they would have to refund the purchase on my debit card as it was purchased with my debit card. The refund has not appeared in my bank account and its been 2 months. Ive contacted the shop hundreds of times and they have either put me on endless hold or took my details, promising to get back to me and not giving any explanation to what may have happened. Where is my refund and why is the customer service so poor when calling??