Broken phone bought from Vodashop

I renewed my contract at Vodashop on the 20th of March and got a new Samsung S9. I took a couple of days to set the phone up and when I eventually started using it, I found that it keeps breaking up during calls which is so bad, it essentially renders the phone useless. I took the phone back and the tech guys made some changes and said I must try again and come back if the issue persist. I returned the next day where they made one final change and said that if it still doesn't work, I must return it the next day (the 7th day) and they'll send it away to be replaced. They said that as long as they book it into the system on the 7th day, then everything should be ok. I returned it the following morning.

Eventually they phoned me last week to notify me that it is too late to swap out the phone because the repair center received it after 7 days and that they're going to attempt to repair it. Firstly, that is not my problem. The condition for replacement of an out of box failure was that I return it to the store within 7 days, not that they must send it away and arrive at a repair center somewhere in 7 days. Secondly, if the tech guys took in the phone from the beginning when I reported it and not send me away to test the changes to the configuration, it would have been booked in long before the due date. Thirdly, I could have gone home to collect the rest of the packaging and bring it back to the store that same evening, but I didn't because they said it is fine to bring it in the next morning.

I voiced my dissatisfaction and they said a manager will phone me back which never happened. I've now been 3 weeks without the phone that I'm supposed to be paying for and when I eventually do get it, it would have already been opened up for repairs. So much for buying a brand new phone from Vodacom.