Web-loyalty company Vertrue hasn't been too loyal to requests by the Senate Commerce Committee for documents including communications with business partners and credit-card companies, so the committee issued a subpoena, CNET reported.

The Senate Commerce Committee is investigating Vertrue, as well as Webloyalty and Affinion, due to consumer complaints that they were tricked into shelling out monthly fees.

The companies operate by extending cash-back and coupon offers to consumers and charging anyone who enrolls in their loyalty programs, CNET reported.