After 3 trys I found somebody in India who could confirm a seat in Y.
However all the agents say they could not book an E+ seat since I had not booked on the UA site or had status. The lesson I learnt is that It does not pay to book code shares on UA through a star alliance partner, since some of the booking featurs are blocked. I am not sure if Oneworld or Skyteam operate the same way. UA did say I could check for E+ on the day of flight, but I could not do it via web check in as, I could opnly do web check in via the AC site. I wonder if I could upgrade to E+ at YYZ since the counters are next to each other, The agent says I could only do it at the RCC or the gate at ORD.
It's a 4:45 flight so the extra room would be welcome.