Checkout solution required for shopping cart booking system

I have a unique seat booking software that is based around the oscommerce php shopping cart code but a little more sohisticated.

My system presents a grid of products with a quantity of 1 and also where products will have more than 1 quantity like general admission.

The system works fine with this principle but the reason why i am here is that my client needs to use the same system but represent 3 days.

So for every product the customer must choose if he wants a 3 day ticket or not.

Initially the customer choosing to add a ticket to the cart will automatically have the 3 day price, but must have the option to disable each day and therefore have the option of a 2 day ticket or a 1 day ticket.

The difficulty is we are reserving specific seats here for each day and they all must be accounted for.

NOTE: each seat cell is a product row in the database with the exception of the General Admission which behaves like a normal shopping cart product with a quantity limit.
I need all options covered for the 3 day festival ticketing including sending the results to the final PDF E-Ticket that is generated at checkout.

I have the whole system loosely set the way i think it should be set with CheckBoxes for Days
where the desable checkbox will remove the product and adjust the cart total accordingly.

Im looking for an experienced open source php shopping cart technician to complete the scripting to make this a reality. (also looking for long term relationship for more similar projects with the same software)

The system is online and functions perfectly as a 1 day ticket system but I need a working solution to extend it to a 3 day system with discounted prices.