The endorsement code relates to the offence you have been convicted of. If you have entered a guilty plea to an offence you do not accept then you cannot change the code. The only way of changing that would be to appeal conviction within 21 days of decision. If you have entered a guilty plea then an appeal against conviction would not be possible.
In any event, a charge of failing to provide whilst driving or attempting to drive does not require definitive proof of driving for a charge to be effective. The officer needs only to have a reasonable suspicion that you may have driven to require a specimen lawfully. Unfortunately, it is unlikely anything can be done to amend the endorsement in the circumstances.
