Hi MrsEileenS,
Thanks for taking the time to contact us via the Community. It's lovely having you on board with us in the Forums. ⭐
We're sorry to hear that your latest bill showed some unexpected charges. When on the old copper telephone system, a crossed line (although rare) could have meant you would have been charged for calls not made however on the new digital system, this isn't possible.
As you've mentioned your telephone line is provide via the hub, this means the calls could only have been made from your line. It may be worth checking with anyone who has access to your house incase they have made the calls.
Thanks,