I'm late replying to this thread but I came on here out of interest because I have a BT Mobile SIM and this has happened to me on 3 occasions, May, June & August and each time they say its You Tube usage. I gave them the benefit of the doubt the 1st time, but when it happened again in June, I'd specifically checked that data was off before allowing my granddaugher 10 mins of nursery rymthms on You Tube, but no sooner had she come off than I got the SMS to say I'd used nearly 5GB of data. After this occasion I cleared the cache on You Tube and disabled it. But lo and behold I got stung again, 2nd August again 4.77GB over a 2 day period. Called up BT again to explain the You Tube is disabled and data was off over the 1st/2nd August as not been out of the house, but again they blamed You Tube. The same reports of data spikes are all over the BT Community Forum too. I eventually contacted a colleague in BT ( I am a former employee) and he put a request in for me via a scheme called "Help a Friend" this gets issue flagged straight to Executive complaints. They looked into it and confirmed that data does appear to be used on You Tube but agreed over 4GB is excessive for 10 mins of nursery rythms. They also confirmed that on the last occasion my phone connected at 12:50am through to 12 noon the following day which they agreed was very odd. I've gone to the expense of buying a new phone as they suggested it could be my handset. Only time will tell if this stops it. My data renews tomorrow, today BT account say I've used 5.25gb this cycle, my phone says 532MB, so work that one out. Sorry for the long reply.
