Deposits + fees will likely never add up to payments
Deposits could be off for 2 reasons (really the same reason):
deposits at the beginning of the month may have appointments from the previous month
deposits at the end of the month may not have appointments from the end of the month if they haven't cleared
The graphs should never be used for any authoritative reporting/taxes/etc...they are just there to give them an idea of what is happening in their business. Reports should be used for exact numbers.