premium increases but my car value decreases mont

I am so not happy about the pricing of this insurance, how come my annual premium increases every year while my car value depreciates each and every month, I tried foning for querying but I waited on the line for more than 10minutes, when the lady answers I told her I am using airtime and I have waited for so long may she call me back she took my contact number but it's been four hours now I haven't received a call from anyone. Can somebody explain it to me why am I paying more and more why the money that I will be paid if something happens to my car is getting less and less???