Disgusting service. Passing the buck,

I bought a phone Huawei Dual sim phone, then after months it stop using dual sim only taking one sim. i took my phone back to exact in July, and was given the run around went back again in September i was told there's a new manager, i told my story she then told me to go to markhams to get paper work i went there i was told they are too busy to help me. i then went back to tell her they must sort it out, its now November nothing has happened and my phone is been in for repairs for 5months. i want a new phone i was treated unfairly this is definitely un called for. Poor service im annoyed.