Big Foot state on their own homepage that they are the only company authorised to run ice hiking and kayaking in the Glaciar Grey and Lago Grey sector of Torres del Paine, and nothing I found contradicts it — everyone else in Natales who sells the ice hike is reselling this trip. Their guides hold certification from the Sea Kayak Guides Alliance of British Columbia, which is an unusual thing to bother with and a good sign.
Two products. The kayak is two and a half hours among the icebergs on Lago Grey, leaving at 08:00, 11:00 and 16:30, at CLP 195,000. The ice hike is five hours, of which at least two and a half are spent walking on the glacier in crampons, at CLP 265,000. Both start from their Base Grey, fifteen minutes on foot from Vértice's Refugio Grey — so you need to be in the park already, which for most people means it is a day on the W rather than a day trip.
They publish no phone number of their own. Email and WhatsApp are the booking channels.