"Wolf Home Security" is indeed a fictional business. However, it is a parody of ADT Security Services. Many of the scenes in this episode are parodies of several commercials for Broadview Security (formerly known as Brink's Home Security and now merged with ADT), including imitating the camera work and the conversations between the operator and the customer.
The last time Cartman said "respect my authoritah" in a South Park episode was in "The Last of the Meheecans", but in that episode, he says it in Spanish. So, the last time he said that line in English was in "Marjorine".