Due to Contractor delivery failures costs for prolonged scaffold duration are borne by who please?
You need to provide a bit more detail to allow this to be answered, as it depends who you are and what you have written into the contract.
If you are the Employer who is providing free issue scaffold to the Contractor - you will have to see within your Works Information/Contract Data to see if you have written anything in that penalizes the Contractor e.g. is the completion of the scaffold a Key Date - for which you would be able to recover costs for any Contractor over-run.
Depends in part on which main option you are using.