Received wisdom is that in order to be offered an SAC the driver's driver nomination form (s. 172 response on the back of his eventual NIP) needs to be received within ~3 months of the date of offence, and the course needs to be completed within ~4 months.
Assuming* that the request for driver's details was an s. 172 from the police addressed to your employer, as opposed to a copy of a NIP received by the hire company, or an invoice for the admin charges, etc., then logically the delay could be down to your employer not having sent the response off, your employer putting the wrong address on it, the CTO taking a while to process it, or postal issues.
As has been suggested, you are far better placed than us to ascertain whether and if so, when, your correct details were sent off, and whether by post, or an online form.
