Combine the refried beans, 3/4 cup of salsa and garlic in a small bowl. In another bowl, combine 1/4 cup of salsa, black beans and tomato. Take 2 long sheets of aluminum foil and make a foil sling. Place in a 5 or 6 quart slow cooker. Spray the foil with non-stick cooking spray. Take one tortilla and spread 1/4 of the refried bean mixture over the tortilla (leave about 1/2 inch of space around the perimeter). Place it in the slow cooker. Sprinkle 1/4 cup cheese over beans. Top it with another tortilla. Spoon 1/3 of the black bean mixture over the tortilla. Sprinkle 1/4 cup of cheese over the black beans. Top it with another tortilla. Repeat layers. Cover and cook on LOW for about 4-5 hours (depending on how hot your slow cooker cooks) or about 2-3 hours on HIGH.