Refund not Received

I'm writing to express my dissatisfaction with the Cellc Gateway shop.

I bought a portable charger for my phone around two months ago. After inquiring and showing the sales assistant my phone, they informed me that it was the charger I was searching for, and I bought it straight away. Because I needed to use the charger, I left the business and walked to a neighboring food place. When I unpacked the item, it did not fit my phone, so I returned it and requested a refund. I was then informed that the refund will be processed within 5 to 10 business days. That never happened; I went back and forth with the store, spoke with supervisors, and so on, but they were unhelpful. They kept sending the store assistant back and forth because the previous manager didn't want to address me. I'm upset by this, as well as by Cellc in Gateway, given that I've been a devoted client for years.