To request a change, just send your cleaner a change request through your online account.
Click on the order from the list of 'Current orders', then pick the specific date and click on 'Reschedule appointment'.
Once you've sent the change request, the cleaner will be notified and will be able to accept or decline. Whatever they choose, you will be notified by email.
We always recommend to agree the changes with your cleaner beforehand to make everything easier.