If you have made a SAR or a request to ACRO then they will reply. It is supposed to be 40 day but may take longer and if they are late the ICO will do nothing nor will they take any action if they withhold anything you later find they have kept. I am sure you will not be surprised by that.I am yet to see what state my CRB is in if they bother to reply.
However a basic DBS(CRB) does not show arrests. There is an information system known as IMS that maybe runs to 3 pages on you but this would not show up on a basic DBS although may well show would on enhanced vetting.
I too have recently had to have certain reports removed from records and there are 3 officers that will not be eligible for any kind of advancement for at least 12 months but in view of your last comments about giving first aid then for me you do not deserve an offer of any type of job.I have been to interviews for jobs since this episode but have not been offered a job.
Obviously only you know if that is the real reason you failed.
I suspect there may be others.