I've just written an article about a recent decision of the Canadian Transportation Agency involving an accessible travel complaint. It's called Accessiblity Complaint Decision.
A couple of things came out in this decision, about the procedure in particular.
The complainant was not the disabled person. The Agency said that the disabled person herself should have made the claim. It wasn't fatal in this particular case, but if the stakes were higher, it could have shut the proceedings down.
The complainant wanted money and free flights because of the discomfort the airline had allegedly caused.
The Agency said it did not have the power to award those things.
Making a complaint to a regulatory agency can be fairly easy, especially as compared to going to court. Agencies often have staff who can help complainants work through the process.
However, most regulatory bodies exist to do very limited things in tightly prescribed situations.
Make sure the one you complain to can give you what you really want.