14707 has cost us money

We have a contract cellphone that security guards at our gate use to contact residents when they have visitors.<br> The number in question keeps receiving spam from CellC, where a person is invited to play in order to win a large cash amount.<br> This number (14707) has no opt-out or STOP option. It seems to be directly from CellC, as the wording is to the effect of \win big with CellC"<br> We would like to know who authorised the spam"