Smile Design Mount Dora

A few months ago I went to Smile Design Dentistry in Mount Dora. I was a new patient and was given a check up, and x-rays taken. Turned out I needed a crown. I agreed to have this done and "asked" if my payment will be any more than the $350 or so the procedure was going to take. They said no, that's all I will have to pay. Being a new business owner, I have to watch my spending because I have zero income. Long story short, I had the crown installed, then about a month later I got a bill from them for $890. Well this got my attention!
I called my insurance company and got on a 3 way call with Smile Design. I had a 12 month waiting period for major work, and I was only 6 months in. Not knowing this at the time, I would have waited 6 months to get this done. Smile Design said that it is there protocol to check the status of people's insurance before work being done. My insurance company has it on record twice that Smile Design declined any check to see if I was out of my waiting period. I think the lady's name that they talked to was Glannis at Smile Design.
After talking to Smile Design about this they said I am still liable to pay. They have since reduced the amount that they say I owe to $620.91. (Seems like they are feeling they are at fault). I refuse to pay this and will fight this all the way. Again, I am a business owner and if I made a mistake and tried to charge a client anyway, that would be totally considered bad business and not caring about clients. I will never lean that way in business. Thank you.
Product_Or_Service: Dental work