(Disclaimer: I am not a police officer, but I have some knowledge of the criminal justice system).
Report every incident/interaction to the police and make a note of the reference number they give you each time. Ask for all the logs to be linked to each other to build a picture. Depending on the type of incident you are reporting and corresponding response time allocated, you will get a call and/or visit from an officer for each incident of reporting separately.
If a phone call, record and/or make contemporaneous notes. If a visit, ask them to use their body worn camera to record; the red light will flash if it’s recording. They can ‘save’ the recording and link it to a crime and/or incident, but this is a proactive thing rather than automatic, so my advice is to also take notes. Take the name, collar number and police station of any officers who call and/or visit you.
As a PP suggested, make sure they take a statement from you (an MG11) and that you sign it. They won’t give you a copy, but it will be available to you if you later give evidence in any court proceedings.
Keep phoning the OIC (officer in charge) and if you can’t get through to them, quote the relevant ref number to the call taker so your phone call is logged.
Also, gather any evidence you can. Doorbell and CCTV camera footage, call logs, messages, emails - it all builds a picture. Ask the force what file sharing platform they use that would enable you to upload your own evidence, ie do the work for them if you have to.
After you’ve been through this several times, make an official complaint to them (go to the force website to find out how, or check the IOPC website, though you need to log a complaint with the force rather than go straight to the IOPC).
The force does not want to hit the headlines for having failed a member of the public who’s been subjected to harassment and stalking and the devastating consequences