I agree with the communication suggestion.
Blowing the clippings helps but it doesn't get rid of them. They might be spread out but they are still there. Shoes and pets can track them inside your customers house.
Next time ask to increase the frequency of cutting (every 5days) to achieve your desired height. This decrease your chances of making a mess or destroying the grass.
Whenever I cut, if I see a big mess I always stop and bump my blades up. Walking through lawns with a blower sucks. If this is the case try going to 5 or 6 days like mentioned until you have your place under control. My nicest lawns are ALWAYS on 5-6 days during the spring. My nicest lawns are also my most understanding customers.