If the telephone utility has undercharged any customer as a result of a fraudulent or willfully misleading action of that customer, or any action by any person (other than the employees or agents of the telephone utility), such as tampering with the facilities, when it is evident that such tampering or bypassing occurred during the residency of that customer, or if it is evident that a customer has knowledge of being undercharged without notifying the telephone utility as such, then the telephone utility shall recover the deficient amount provided as follows:
S.C. Code Regs. § 103-623.3