IMO, the OP should have boarded the YYZ-MUC flight without complaining at Toronto and asking to be rebooked at MUC.
In the current situation, it seems that the OP has lost a day and probably paid their own hotel in YYZ + their expenses as they have volunteered to travel a day later. The airline had offered them a better re-routing ( obviously in their own perspective ).

If he had gone to the MUC transfer desk being quiet at YYZ, he would have received a minimum ( 300 EUR x 5 = 1500 EUR ) in cash and would not lose a day but only hours.

By the way, MAN to AGP is also served by BA CityFlyer and Iberia ( possibly IberiaExpress ) during the summer season.