BAD SERVICEM

I renew my cellphone contract in Keywest in December, the Samsung A80 they give me was faulty , took it back the next day to be replaced , however the salesman told us he cant replace it , he is waiting for a batch of phones , no stock available, after waiting a month he told us the phone is in for repairs, we told him we don't want a phone that was to be repaired we need to get a new one. this is now May , no phone paying for a phone we don't have . I am a customer at MTN for many years (20). The service at MTN Keywest is the worst service ever, I need a number and name of who can assist me, I am fedup. Marlene Roets