Hello,I am a solicitor with 20 years experience. I will try to answer this for you.
If you were caused ABH or GBH there is no time limit on a prosecution if there were no injuries then the time limit has long passed.
He was also given a caution. This is an alternative to charging and someone in a responsible position at the police made a decision (at least partly informed by your views at the time) that it was not in the public interest to prosecute him. On this basis he accepted a caution.
It will be impossible to resurrect this case and have him charged.
I do not know what has happened with the phone call request. Will make enquiry with the site.
As far as a civil action iss concerned that is unikely. You will be out of time for bringing a claim (3 years time limit for pesonal injury actions, and & 6 years imit for most other types of action).