Couple ideas for more scenes.
Desperate Customers: Random customers will be desperate to do their laundry and if told 'no' they may offer something. Alternate would be customers who forgot/don't have their money being a random occurrence.
Angry Customers: a few scenes to make up to customers for doing a bad job (underwash/overwash), or to perhaps change their minds.
Dealing with the Police: Have a few options to get the police suspicious and ways to throw them off. Maybe some time locked in the washer to brainwash them?
RPG Elements/Upgrades: An actual economy system, IE you need to make X amount of money every day to keep the lights on. For example you'd have 5 washing machines in your shop to start with, buy more/better machines. Maybe some strange washing machines this pink fellow with slimy hands in a trench coat is offering to sell. Telling the girls to work off their debt actually has them work for you (temporary automation for washing machines, potential boost in business due to full/half naked washer girls, or extra profit for 'full service' (take that as you will).
A whole lot of ways to go with this.