If the ticket says speeding 80 km/h in a 50 km/h zone, and the total payable is $140 (or even the set fine for that matter), then yes, you have a ticket bearing a fatal error. You may be interested in reading this thread:
http://www.ontariohighwaytrafficact.com/topic1598.html He was ticketed for speeding on the Don Valley Parkway in Toronto, but the set fine and total payable were not correct on the ticket. He did not show up for his trial. Actually, he contacted the Prosecutor and said "are you going to withdraw the charge?" When they said "no," he did not show up. This meant that the JP had to examine the ticket to make sure the important parts were right ("complete and regular"), and if they weren't, he was supposed to throw out the ticket. Unfortunately, the JP erred and entered a conviction. So Off_Camber had to appeal... and he won.
Smith v. City of Toronto This only works if you don't show up for trial. If you do show up, they can fix the error. If you don't, they can't. Be ready to appeal, though. Usually the JPs simply enter the conviction without examining the ticket to see if it's properly made out, so an appeal is usually necessary to get the ticket quashed. That's because most JPs are political appointees who have been to 2 weeks of JP school and never attended law school; Justices who handle appeals and sit on higher courts have been to law school and have substantial legal knowledge and experience.
If you do use a paralegal, discuss this particular option with them. Do some research into it and see what you think. It is possible to do it yourself but if you have any doubts hiring a professional is never a bad idea.