Is there any way to book a different number of visits for different days?

If I need two visits on a Friday, three on a Saturday, and two again on Sunday, that would add up to seven visits. But when booking I only see the ability to set the number of visits per day for the entire scheduled block, meaning three days worth of three visits, nine in total. I will end up paying $50 extra for 2 visits that will never happen and service that won't be provided. Is there some way to adjust the number of visits on individual days? I have met with the sitter and he understands I only need the 7 visits. How do I get this reflected in my bill?