Edit your network interfaces file in this way and reboot your Pi. Before editing this file you should take a backup for revert back this file, if any problem encountered.
auto lo
iface lo inet loopback
auto eth0
allow-hotplug eth0
iface eth0 inet manual
allow-hotplug wlan0
auto wlan0
iface wlan0 inet dhcp
wpa-ssid "Wi-Fi username"
wpa-psk "Wi-Fi password"
There is a problem this configuration that it do not allows you to search for a network and connect. If you know the ssid and password you can connect to network without any problem.