I bought the whole kit from Halfords - the front and rear camera also the hard-wire kit for the rear camera. I had the kit professionally installed with a direct power source to the car battery. The camera starts up on ignition and I also have the settings on parking mode.
The only issues I then had were to adjust the settings and getting the camera to record simultaneously.
At this point I share your frustration because it was not recording properly and was on the verge of taking it back and demanding a refund. I found this group and the support from Next base very helpful in helping me to solve the issues I was having.
Eventually, through of lots of investigation (and determination) I took the SD card back to Halford's who replaced it for me. (I did buy one myself and found it was not suitable for the Nextbase model) If you need a replacement SD card make sure it is a Nextbase card.
Today, the camera is working perfectly fine just like it says on the box, front and rear recordings are very clear and simultaneously parking mode is working fine, I don't have any power issues as it's connected directly to a power source. The only Issue I now have is with Alexa and blue tooth - I didn't buy the camera for Alexa, so I simply don't use it.
Nextbase software is also very useful to download onto your P.C.
Stick with it...
