Huawei Y7

Good day, Please kindly assist i recently bought the Hauwei Y7, within 6 months it started giving me problems touch screen not respomding smoothly, the network has always been bad, it always goes to voicemail even when its on, i took it back to edgars randburg and was being assited by a gentleman called Bongane, very friendly and willing to help, phone went for repairs, and came back with a message saying screen is cracked, to both our surprise we took it back, recived a call to collect it today and nothing has been done on the phone, we charged to see ,the crack nothing, when i returned it for the 2nd time i asked where is the crack, and is the crack part of the reason why it has no calls coming through? but no response, ive just charged the phone and realised it still has my pin and if it was touched it would have been reset with no pin, please advise as im very annoyed and dissapoined with this matter not being resolved and its Inconveniencing as i currently do not have a phone.

your speedy feedback will be highly appreciated, i have all documents with me should you need.