Unless policy has changed, Remington will not sell a bolt or bolt body. They are available for factory fitting, or for fitting at a factory authorized depot. The barrelled action must be sent in. Contact Remington for authorized service centres.
If a spare bolt can be found, it would have to be fitted; there is no guarantee that headspacing would be correct. AFAIK, Remington makes bolts with three sizes of boltheads, and selectively assembles.
As Rembo mentionned, the tube could be replaced. This would not be a job for the faint of heart. The bolthead is brazed and dowelled in place, the bolt handle would have to be correctly brazed in place, the threads for the bolt plug would have to be cut, as well as the cocking cam.
There are aftermarket Remington style bolts made in the US, used by the target & benchrest shooting fraternity. I do not know if these are available in Canada.