Change Quantity not right for Appointments+ product

Hi

When a customer books an appointment on my website they have the ability to change the quantity due to the way Marketpress is written

See Screenshot. Basically I believe we need an additional product type in Marketpress which is "An Appointment" so that if anyone books an appointment they're not able to change the quanity in the drop down box of the check out page

Hope someone can help fix this bug because at the minute clients can book two appointments at the same time that I can't complete.

Kind Regards
Kieran