1SIM phone in for screen repair comes back DUALSIM

I took my single SIM card Sony M2 phone into Vodacom repair centre at vodaworld midrand to repair screen flickering and vertical lines on the screen. The phone was booked in for repairs, when I went in to collect the phone I was given a Dual SIM card phone. I returned the phone and informed Vodacom that I do not want a Dual SIM phone and that if they want to change my phone they must give me a new phone, not a used one. The phone was then taken in again to rectify their blunder. A week later a received an SMS to collect my phone and I was presented with the same phone I returned. <br> Now my phone has been booked in at Vodacom for almost a month for a week worth of repairs without much of an explanation from Vodacom.