When we have a client booked in one day (they have been consulted, receipted and checked out) and then they come in again the next day or 2 days later or even that same afternoon for a follow up visit, when we try and invoice, the system will not let us! It still has the last invoice sitting there as if it hasnt been finalised, yet it says it has been finalised! Really really strange. :(  please help :)