Your memory is in error. 2yrs ago you could not purchase Offense repair time as a crate to go in resources, only as an increase in capacity. They introduced the ORT crates after a particularly bad period of downtime and were only available as a gift from them. More recently they have added them in the Premium packs as well as still including them in the gifts after poor server performance or other issues.
I don't quite follow your explanation of what is happening - when you attack a base you have injured or damage units. Each type of unit requires the appropriate resource building such as barracks for infantry, factory for ground vehicles and airbase for aircraft. The amount of repair time is calculated for each type of unit and your overall repair time needed is the maximum of the 3 types. This is then deducted from the available repair time. You will see two figures, such as 2d 12h for the capacity (on the right in white) and the amount accumulated overall over time. This will stop increasing when you reach your maximum capacity. If you are at maximum (at the start of a session, more than likely) the total available and the capacity will be equal and shown in red. As you consume repair time it will change from red to yellow indicating you're close to capacity and if you consume more then it will turn white.
You haven't included an image so I can't see the detail of what you're referring to.
Image showing repair time total in yellow as it is close to the maximum of 2d12h.
http://prntscr.com/l0i7fi
The white cross on the red background next to the yellow writing indicates I have some of the repair time crates in my resources area.