cell phone repair at pep cell

good day o the 2017/12/16 I bought a cell phone at Pep Cell jubilee Mall. the phone was mobicel ber. I used it until January the 26, and it stop working, I have to take it back to Pep cell jubilee Mall on the 2018/02/05 for repair.

they told me that their gong to access it and they will inform me the process of it. since February I visited them twice with no luck of getting it, now its mid April, it is almost 3 months without my phone I also suggested that they give me money back or new cell phone, and they told me that their waiting for authorisation, they will call me back, iam still waiting for them. it is frustrating me, may you please help me