The three numbers that matter
Sessions purchased is everything you have ever bought. Sessions used goes up when a session is completed and logged. Sessions remaining is the difference — that is the number to watch.
Cancellations
A session cancelled with at least 24 hours notice is not deducted. Inside 24 hours it is deducted, because the time was held for you.
Replenishment
When you drop to two remaining sessions, a replenishment request goes out automatically. Approving it keeps your schedule uninterrupted.
Something looks wrong?
Message Dave with the date in question. Every ledger entry is timestamped and append-only, so corrections are logged rather than overwritten.