Poor Service delivery

I bought a cellphone April 2017 at pep stores Carnival mall.I did not even have my new phone for an entire month and had to take it back because of not charging properly.The consultants excepted the phone back and told me it will take about a month for them to investigate and I can then return back.I have often take out time after a month to go there and query about my phone but each time I get there they give me different promises.I was suppose to have it last week but the consultant just shrugged her shoulders cos she is also trying everytime to call their head office to find out where my phone is as they have promised to give me a new phone as this one is faulty..Not once since I have returned the faulty phone have the contacted me as promised to update me or any feedback. this is a High sense that I took in 03/07/2017-u601S.I am so dissapointed in your poor services received.If I do not get a resolution I will be taking this further. Unhappy customer