The following may not constitute sufficient cause for refusal of service to a present or prospective customer: Failure of a prior customer to pay for service at the premises to be served; Failure to pay for merchandise purchased from the utility; Failure to pay for a public utility service other than water service; Failure to pay for a different class of service; Failure to pay the bill of another customer as guarantor of the customer; Failure to pay the undercharge for the period in excess of 4 months as described in Regulation .06E of this chapter; or Failure to pay an outstanding bill that is over 7 years old, unless the: Customer signed an agreement to pay the outstanding bill before the expiration of this period; Outstanding bill is for service obtained by the customer by means of tampering with equipment furnished and owned by the utility or by unauthorized use of service by any method; or Outstanding bill is for service obtained by the customer by means of an application made: In a fictitious name, In the name of an individual who is not an occupant of the dwelling unit, without disclosure of the individual's actual address, In the name of a third party without disclosing that fact or without bona fide authority from the third party, or Without disclosure of a material fact or by misrepresentation of a material fact. This regulation applies to both residential and nonresidential classes of service.