Is there a way to prepay the TINDR1 code online?

I booked a 5-day rental with this code and saved over 50% on the rack rate. I'd prefer to prepay and simply go to the kiosk with my ticket if possible, so as not to deal with customer service at the counter. I can't seem to figure out how to do this though. It seems as though you cannot prepay rentals when using a Contract ID for some reason. Unless I just can't figure out how or where to do so. I'd greatly appreciate any help with this, as I'd like to ensure a smooth pick up with this reservation. On a side note, does anyone know what the above mentioned code refers to; I assume a corp. rate? Any info would also be a huge help.

Thanks!