Faulty New Phone

I recently upgraded my cellphone contract and I have been having problems with my new phone, it is slow and the has a faulty network operation. I took the phone to the store and they told me to take it to Samsung if or check up. I took it to Kollonade and Brooklyn and then they updated the software BUT it still has the same problem. At the store level they said I need to book it in. I will not be having a phone for 2 weeks after upgrading for a brand new phone and they will not be giving me a loan phone on top of that. It's been 4months using faulty phone, please help