The same happened to me. All my 3G data gone in one day because a friend uploaded 700 pics to a shared photostream.
I can find no way to turn 3G usage off for this feature the way you can for Face Time.
There should be an option to limit shared photostream to WiFi only. I have send a request to Apple for this feature, and encourage others to do the same
Have you tried the Settings/General/Cellular and turn off iCloud Documents?
The Cellular option may be Mobile or similar in other countries. Personally, I know this may not be an option in all areas, but I wouldn't own a smart phone with out unlimited or at least a 5GB limit or higher. But I am a heavy data user and regularly use my iPhone's hotspot while on the road.
I can only assume you are streaming video since this is one of the biggest consumers of data. I would think you would have to take a lot of photos to have a big impact on your data with Photo Stream. My iPhoto Library of a little over 2000 photos is around 5GBs. Most of these photos are taken with my 12 megapixel Canon Rebel. So even if you are using a newer iOS device with an 8MP camera, 1000 photos, even if you estimated high at 2-3Gbs of data, is not that much compared to a 15GB plan. It may help but in my experiance that would only get you another couple of hours of streaming HD video. You would be better off streaming SD video if available which would cut down considerably on the data use.
I will agree with you that turning off iCloud documents should turn it off, but for the amount of data it uses, I would sooner have my Photo Streams auto syncing rather than download a few more minutes of video.
I suppose you could disable Shared Photo Steam while you are at cellular network and enable it again when you are at a wi-fi environment. In Settings>iCloud>Photo Stream> turn Shared Photo Stream to Off.
The pop up warning tells you that this will delete all shared photos from your device. What it doesn't say is, since shared photo stream remains stored in iCloud, all you shared and shared with you photo streams will be push back to your device once you enable Shared Photo Steam in wi-fi. The downside of course is if you have a lot of photos in your shared photo steams, it will take some time to download them. But at least you know for sure your cellular data is not affected.
Btw, Shared Photo Steams doesn't count towards iCloud storage, just like Photo Steams. Maybe That's why turning off iCloud document doesn't affect shared photo steams.
Guys, I have a different problem with Shared Photostreams.
I was organizing some photos - uploading them via PC to iCloud.
They got automaticaly pushed to my 3gs that was connected to my home wifi.
After some time I got a message from my carrier that my data plan was at 90%.
Was stupid enough not to check cellular usage in 3gs - only checked if its connected to wifi - it was!
After some time I got again a message that my data plan was consumed and I will be charged any additional data usage.
When checked cellular usage - I was ca 1Gb over my plan which will be quite expensive
Anybody had a similar issue?
Any suggestions what should I do?
If you will be doing some mass upload - turn off your cellular... JUST IN CASE...
I have a Laijkaboss similar problem with shared Photostream on iOS 7:
Even if connected to the WiFi, after having organized several photos and videos in Shared Photostream, I noted that the cellular data consumption was 0.5 Gb!
I presume that uder WiFi connection, all the operations will be carried out over WiFi and not over Cellular data!
Any suggestion on the rationale of this strange behaviour? How to stop this anomalouos consumption?