The next clean date is dependant that payment was received from the last clean by the time the next is due.
When I say I don't enter into a dialogue with them, what I really mean is I do not enter into drawn out conversations or wordy texts.
It's the same template text, it goes out to all customers one week overdue, daily until it's either paid, or they respond with the mitigating reasons why.
For example, if a customer replied to me something like.." We have been in hosptial" i would simply say, Thank you for reply, I will withhold reminders for the remainder of this month, best wishes StockClean.
It's not rocket science.