New Phone repaired twice already

I bought a cell phone at Truworths mall of the south earlier this year then it had a problem i called they said i must bring it for repairs within a month it after it was repaired it gave another problem when i called and asked why are they not giving me a new phone because every time i take it for repairs i m left without a phone i was told i did not sign for phone replacement it was repairs which i was not informed of, they really are disappointing and for the fact that I m paying for the phone which is always going for repairs its theirs and im paying for it still...