Contract phone complaint

Good morning On the 12th February I purchased an OPPO phone with contract for my wife. She received it on the 14th midnight as a birthday present, she loved it but was not happy with the picture quality and also the speaker volume low. We made the store aware in the morning and and they advised maybe the settings are not yet in order. Over the weekend we tried and eventually went back to the store on Monday(19th) - we compared the picture quality with the OPPO next door in Vodacom store of which it was way too different (same phone different picture quality). The store decided to book it for repairs of which I made it clear that I will not have a phone from repairs that I haven't even used so they better give a replacement. Yesterday (4th March) I went back to the store but they wanted to hand me the same device from repairs which I refused and left in the store. Who buys a brand new product only to repair it before use? This has been a frustrating, time and energy consuming exercise - today I waited for more than an hour for the manager to attend to me but in vain. MAY THE MANAGEMENT OF TELKOM INTERVENE NB: The store in question is Telkom at Mimosa in Bloemfontein.