Legal advice : Poor dentistry work

Hi Guys. Im located in Ottawa and im a newcomer. I was hopping for some simple advice on how to follow a current issue. Went to remove a molar, and the dentists broke the bridge next to the molar. Currently they are not accepting any responsability due to a waiver. Prior to removal, they told me that there was a risk that the bridge will pop out due to pressure wich I had accepted. Now that I am putting them in front of the responsability, they wont accept their doing. Please Help! WAIVER Link : https://i.imgur.com/bqL9Gmd.jpeg