I just had the same problem last night and I have gone through, literately, hundreds of posts and this is the first one to offer the correct solution.
Thank you for helping.
I cleared the data in the app manager and it fixed the problem. I then removed the app because... well... that should be obvious.
On a side note, I've had this phone since around June of 2014 and never had this problem. But my DSL went down for a week (Thank you Verizon) and I had to use the S3 for all of my normal net stuff.
Isn't it funny that when my data usage spiked, but was still way under their bar, they decided to force my wifi on? Maybe to get me to, unknowingly, use wifi whenever possible rather than their data? Which would certainly be to their benefit. Seems a little slick to me... but still, I'm happy with my service and I can afford it... so at least now I know that I need to keep an eye on them a little bit.
I guess this is why I can't use my S3 as a hotspot as well... which really would have helped during the outage.
Thanks again guys. Y'all are great (yes, I said y'all) and I'll try to check in here when I can.