Joomla / VirtueMart Work Needed

Need experienced coder to help with editing VirtueMart. Have installed a calendar in VirtueMart, but need changes made/ code added to existing installation. We have the calendar in place, we need to work on the delivery times. The overall brief is to allow customers to choose a day (from existing calendar, so that is done) and then select from two drop down boxes, one for AM and one for PM. If the customer chooses PM it starts at 8pm, then 7:30pm, then 7pm and so on (reverse to starting at 12:30pm). If a time is selected by one person then it will be removed from the drop down box for that day. This is what is needed to get the above done. 1) To make the field in the database to write the delivery time which the user will choose from either dropdown . 2) Once a date is chosen by customer, it needs to be checked against data/time in the database. If that time is yet to be chosen, the data (for delivery times) will continue to show. If another customer has already booked that time, then that time will be hidden for that particular day. 3) The chosen data has to be written as the Delivery time in the checkout, in the email - everywhere the calendar shows in frontend and backend. Any questions, please PM. The original delivery date & time code can be found here [login to view URL] (That is what was used in the site). I have an excellent idea about how much work is involved, and how much it should be , so please don't start bidding some outrageous amounts. I need experienced coders who will see a solution very quickly. Good luck.