I have called M&M 3x and AC 2x. To recap: my flight OMA-YYZ-WAW had the segment OMA-YYZ canceled. It was (auto)replaced with ORD-YYZ on AC. There is a revenue option in UA to get from OMA to ORD in time. Here is what each airline/agency has been saying consistently. M&M (the ticketing agency) advised that AC (operating airline which canceled OMA-YYZ and replaced it with ORD-YYZ) must add the UA OMA-ORD segment to the reservation. Once this is done, I need to call M&M to re-issue the ticket. M&M has notes on my reservation to that effect. AC advised on a second call by a very competent agent that normal course is for the ticketing agency to call the operating airline directly and not have the customer do the leg work. (M&M is telling me they cannot call outbound). Regardless the AC agent advised that she added the segment. Upon calling M&M I was told that nothing was added. My next step is to call AC again and this time I will check the record locator while on the phone, once (if) the agent tells me again the new segment was added. At this point (if it happens) I am (fairly) confident that M&M will reissue. It's an interesting experience to say the least. I am also considering calling AC and then conferencing in a M&M agent to do a three way call.