Hi all, new here to the forums and thought I may be able to help out.
There is a little known system in Canada called CAMVAP it is designed specifically for situations like yours. I have actually been through the process on the dealers side and it seems to be a very fair way to deal with issues like this when no other satisfactory resolution can be met.
Anyway, check out the link, it may help.

arbitration, arbitration dispute resolution - Canadian Motor Vehicle Arbitration Plan