NEC ECS: Who pays for the costs of correcting defects under Option B?

We have raised a defect on the subcontractor. The levels are incorrect on some blockwork., leaving the openings too wide. I understand they get paid for the initial work but who stands the costs of repairing the defect?

On an Option B, the Subcontractor should correct at its own costs.

Under option B the Contractor is paid in accordance with completed items on their activity schedule. Therefore if they do one thing twice, there is only a mechanism to get paid once so therefore the Contractor pays for correcting their own defects. This is the same principle for option A.