ios 8 made my iPhone unusable

I recently downloaded ios 8.1.3 to my iPhone 5. Ever since then phone will not connect to most wifi networks that other iPhones, Android phones and laptops all connect to without trouble. I followed all online advice (I have been rea**** advice columns etc for 2 days) but see the problem is being experienced by hundreds (or more) users around the world. Apple support says that after 90 days no complimentary support is available - but Apple provided the ioS upgrade that has now rendered my phone useless as a smart device. I cannot tell how to get support as between Apple and the various service providers responsibility just passes from one to the other. What should I do next?