Runway Powersports Andrew Maloney Is demanding $5300 for changing some cosmetic parts on a motorcycle, without our consent. Trenton, Ontario

After dropping my motorcycle and breaking some of the plastic, I decided to take it to a new motorcycle shop in the area to have it repaired. My wife and I explained to the owner that we were not willing to spend more than $2000 on repairs and we were to be notified if the repairs were going to be that high. The owner suggested that we put it through insurance, he said he would put it in a parking lot and fake an accident then call the police. We would not agree to this.
We did not hear anything back from the shop so my wife was continually calling to find out the status but was always told not to worry about it that they will take care of us. Even when she asked about the cost the answer remained the same. They said they couldn't call us because they kept losing our phone number. We also stopped by every now and again to try and see the progress and get a quote but got nothing from them.
Finally after 2 months they said the bike was ready. We went to pick it up and we were hit with a whopping $4000 bill! My wife and I were both floored but we wanted to get the bike out of there asap.

 Upon returning home with it I soon discovered many parts were still broken and some of the parts that were installed were done so incorrectly. As an example they used black electrical tape to wrap around the ram air box covering a hole that was in the top of it and left the tubes feeding air back to the breather dangling. 
I have since fixed some of the parts myself but am waiting on money to be able to fix the rest. 
They are now trying to charge us $5300. The best part is we had never received a bill from them until the day my wife put a stop payment on one of the checks. After receiving the bill we noticed they put insane markups on most of the items. Some were marked up by $200 and even as much as $500. We never would have agreed to paying this much had he told us what was going on. We have so far given them $2500 which is more than fair for what they have done to it, and we are refusing to pay anymore unless it is court ordered.
The owner is belligerent & trying to use scare tactics to the point that we had to involve the local police.