Apologies for the vague title.

Basically, I have a 4 hour layover at YYZ at the end of the month, and my girlfriend decided to book our flight through a travel agent. Because of the length of my layover, I wanted to pay the $50 for access to the lounge as my fare is apparently S (Flex), but the AC rep on the phone said no dice since the booking wasn't through them, and the option to do so online is greyed out.

My question is: is there any way I can gain access to the lounge, either by smiling nicely and paying at the entrance or by using voodoo magic and booking beforehand?