Trunk Key Don't Work?

I have a 97' mystake, the key does't work on the trunk. Its the right key cause every once in a blue moon I can get it to work but I have to jiggle the key and push and pull and well lets just say it more work than worth it. I had to do it once cause i was messing around with it and accidently turned the remote access off so the trunk release wouldn't work in the car. which also sticks once in a while in the cold. it won't stay released so you need two people one to pull the release and the other toopen the trunk. I tried wd 40 and a de locker on it for both probles and doesn't work. Any answers on either the key problem or the sticky release. How much would it cost to replace the lock and have it keyed with the same key