Online Voucher Booking System, for a webeden website

I am after a voucher booking system similar to that on redletter days.co.uk, where by when a client purchases a item a unique voucher number is generated for them, and together with some other personal details they can "login" to select the option of when to redeem the purchase.

From my point of view, I wlll need to be able to log in to the "backoffice" and change what different dates venues wish to offer this service on, IE have black out dates and times...., and all the usual side of things to do with back office, eg generate voucher numbers, delete edit etc.

I got this done before by some cowboy developers and was not impressed with the outcome..