Phone doesn't disconnect

I have tried calling cox several times all they say is everything looks fine on there end. When we are on one line and other person puts us on hold we end up hanging up, problem is our phone will continue ringing for up to 10 mins! We have called other person back and told them to hang us up. They tell us they have they have a dial tone! Our end still rings! The last cox person I talked with said I needed phones that I can program to end calls on disconnect I have tried to find some but no such luck! Other tech told us to unplug phone line from wall we have 2 after unplugging them we last our phone lines for about 10 mins! This is ridiculous we never had any issues with this until we switched to cox. Which we were told we were on standard analog system which isn't true they now say its digital! Not sure if that's part of issue. Has anyone else been having this issue if so what helped? Does anyone know of phones that disconnect on hang Up?