Need soome advice guys!

[tunedTECH]

Ok here is a story.

I have signed a contract for making my website. so i paid 50% deposit and 50% when its done. but then i was really get disappointed to their service because it was to slow and cant do the job how i really wanted. so i have take some action and do some research how to do thing myself and i finally managed it all. now they emailed me again about the job and show me some progress after i did everything already, well most of the part at least. now i told them that your service was to slow and i did it myself instead and told them that i was really disappointed. I know that i already wasted money paying them a deposit and now asking me for the rest of the money which they never done anything good to my site really. so i told them that i am not going to pay the rest because i have done all the job myself. so my real question is if we put this on court you think that i am able to win it or not?

Help and suggestion would be really appreciate it!