I was in the 42nd Street Library the other day and looked up Friendly Frost snooped in the New York Times archives.
In 1979 Friendly Frost had 37 appliance and audio centers in the metropolitan area and 19 retail garden supply centers.
Also part of the WTFM complex was a high end audio store called Volare Salon which sold audio and television equipment from $500 to $5000. In a newspaper article Friendly Frost said that every purchase from Volare would come with free service for a year. And they boasted "And if the customer doesn't call us, we'll make a service check every ninety days, anyway."
In the 70's, they also expanded into coin-operated laundry equipment.
In the 60's, they also owned WGLI, AM and FM.