irregular charges for repairs

i bought an MTN steppa tablet on 01/05/2016 the phone was damaged within 2months of purchase. i kept the phone ast it was a minor damaged, the headsets slot was not working. it then later gave me problems with the buttons on the screen as it was a touch screen phone, then the charging system and i took it in. i was told it would take 3 to 4 weeks for the assessment. eventually i got an sms to say i must pay R1200 and some rands for the repairs. which i think is crazy as i bought the phone for R999.00. please help with this matter as i need the phone ASAP and im not willing to pay R1200 for a phone that costs R999.00.