Hi guys, I need some more info about my case as I searched and didn't find too much info.

I've booked tickets for my friend and I MEX-MIA o/w on AA metal with Avios. Now she has changed her plan so I need to cancel her ticket. I've tried cancelling online for her ticket only but the website said Cancellations will apply to all passengers in the booking. If you do not want to make the cancellation for all passengers please contact your local British Airways office.You may be charged for offline service fees.

So if I call 800 452 1201, can I assume that agents know how to cancel one ticket while keep the other under a two-ticket reservation? Are BA agents clueless as DL's? I'm a little bit concerned that they might be ruined my reservation as too much pain gained from dealing with DL..

Also I know that I need to pay $40 for online cancellation (or will be refunded fuel surcharge minus $40) and get the 10,000 Avios redeposit, In addition to that, will I be charged for $20 phone agent fee?

TIA!