Agree with Brian. I also have a degree of knowledge in this area, and I belive you have been left-shouldered.
Although 'damage only accidents' are now classed as 'non-recordable' to the police, this is only if details are exchanged and there are no injuries/offences involved (i.e. due care)
This driver has failed to exchange details, and the accident is therefore deemed as a fail-to-stop, which IS recordable, and needs to be reported. He has already (allegedly)commited an offence of driving without due care & attention, from what you have described, which would also make it reportable.
The police are therefore obliged to report and investigate this matter. I would suggest that you re-attend the police station and ask to see the duty inspector to complain about these facts, and have the matter re-addressed. If you have the registered number, there is a blatant Neglect of Duty on behalf of whoever you reported this to. (civilian employee or police)