Faulty Laptop Taken by MTN Morningside Branch Manager

The Branch Manager of MTN Morningside Branch by the name of Sandra Zwane took my faulty laptop for replacement and promised me it would be replaced. I have been there to enquire as to when it will be replaced but have received no committment. She promised to send me an email confirming what she verbally committed to, that I will receive a replacement laptop but that email has not been forthcoming. Every time I call her or send an email she ignores my calls and emails. I have virtually lost my laptop.