PHONE-HUAWEI P8 LITE 2018

I have bought a Huawei P8 Lite, 2017, less than a month ago. After approximately a week, it started to make funny stripes all over the screen, and it responded slowly. I can't use it. Everytime I went to Markhams, the manager was not there. Eventually, after another week, I got reach of her - I asked isn't there any way they can exchange it, seeing that the phone gave problems ever since I bought it. She said I must bring the phone back and they'll see if they can send it in. I took it in yesterday, after I had taken my photos and details off. The manager was once again not there. The two ladies who assisted me- wasn't of any help. I asked isn't there anything they can give me, proof, that I took my phone in. Can't they call head office to exchange it, as the phone is brand new and giving problems. They couldn't even give me a receipt that they took my phone. I asked how they going to know its my phone ; How they going to contact me, They said I must just write my name on a piece of paper and that the manager will call me right away, when she comes in, up to now, no call ... Haven't heard anything. I just feel it is very disapointing- Cant they just exchange the phone as ever since I bought it, it's been giving me problems. now my phone is there and I have no proof that i have given in my phone..... NOTHING. I think this is poor service!!!