I've had something similar before might not be related but I'd forgotten to turn off premium texts or something like that so even tho the limit was set to £0.00 they still got that out. It was a long time ago so that may not be the case now but might be worth just double checking the other restrictions.
Interesting side note having the limit set to £0.00 stops you calling 101 as its a chargeable call, found that out when wife wanted to call police when son was badly beaten at school.
Hope you get it sorted
Thought 101 was free as of April.