Lenovo — Wifi and touch

Sir,
I purchased a lenovo A7000 model smartphone last year in the month of April. Initially the phone's WiFi worked efficiently but now its not. Its WiFi's range has been reduced considerably and moreover it is now not able to grab as much speed as earlier from the same network. Moreover, it now takes longer time to connect to the same network connection and sometimes it is not even connected to the saved connection. There are instances when the connection is not even detected. Now it is troubling a lot.
In addition to this, there are cases when the phone's keypad stop working for a couple of seconds and causes delays in typing. Moreover, it sometimes gets hanged and i had to forcibly lock the phone so that it may work.
As the mobile phone is in warranty period i request you to do the needful. hoping for an early response.
My email ID is [protected]@gmail.com