Stylo s551 2nd phone dead

I bought a phone at pep on 24 December '17. took it back cause it did not switch on 26 December. Then they swapped the batteries and the phone went on. (satisfied) used the phone for a week and it just died (enough battery life on it. 2 January) Took it back and it was sent for "assessment" for 2 weeks. Then got a new phone 23 January (same model) again used it for 2 weeks and it died 10 February. im so ****ing ****ed. I use my phone to get home at night and both times i was stranded at work at 1am. I want my money back like i requested before but instead you decide to make a fool of me again. THIS PHONE NEEDS TO BE TAKEN OF THE SHELVES !!!!!!!