Scheming Pharmacy- Lack accountability and knowledge of the medical field

No accountability for incorrect medication. I have been a customer for over a good few years. I recently sent my prescription via their WhatsApp line to order my medication for delivery, prior to confirming payment done via eft because it was a high value product, I confirmed if they had what I needed in stock, the lady who was dealing with me said they did. Before delivering, a call was made to me regarding delivery. When I received my medication, the label was blocking very crucial information, I opened the box to confirm with my GP if that was the correct meds. He then referred to the prescription he wrote that clearly details the dosage as well as the pen size. Upon hearing this, I contacted the pharmacy regarding the wrong medication delivered, they tried to convince me to take it but I was skeptical so I asked for a refund so I could save for the correct medication as it was costing me a R1000 more. The lady at the pharmacy agreed, when my partner got there, the manager Jeremy at first said they don't accept fridge items back, when I had brought up that it was the incorrect pen over a phone call , the manager says the box has been opened, thereafter asking me if I had told the lady over WhatsApp that I had opened the box, I took a picture of the pen, common sense would've told anyone that the box had been opened. The manager then says he's unable to assist me. I have no option but to submit a formal complaint against the pharmacy for negligence on their part and not taking accountability for issuing incorrect medication.