WiFi problems have been around as long as there have been WiFi devices on all hardware. Go to support sites for any mobile device and you will see WiFi issues so buying other products may not solve your issue.
It may indeed be a hardware issue that became evident on your iPhone during the upgrade. Have you had your iPhone checked?
Apple rarely announces what they are doing with issues like this. With WiFi they might as well issue a blanket statement that they are constantly working on it (and they are). Go here: http://www.apple.com/feedback/ipad.html and enter detailed information about your issues and have your phone checked out.
We are all users here, just like you. Use this link to tell Apple directly:
Did you already try all the troubleshooting mentioned in these articles?