I updated my 5c to ios8.3 and since then my phone disconnects from my home wifi at any given time.

Since updating to ios 8.3 my phone has trouble connecting to my home wifi. It also disconnects itself from my wifi at any given time, so that when it does this at night I wake up to find that I have been using data all night long. This will soon incur me charges that I don't want.. Also, when I close an app it often brings up the screen to put in my apple password, like when I want to purchase or add an app. I have to cancel that out to continue with what I wanted to do. Annoying, but at least that won't cost me money. I went thru the steps on this website and they want me to send in my phone for replacement. I don't want it replaced I just want to tell Apple they need to fix this update ASAP. How do I do that? thanks for any help you can provide.