I hope it's OK to reopen this thread as my situation is similar (but worse). For an avios upgrade WTP->CW (YYZ-LHR return) I was quoted over £1100 for the cash component (and 40k avios). The agent couldn't give me any more details regarding how this is calculated.

Two questions if you wouldn't mind:
1.) Is £1100 for a return TATL UUA WTP->CW "roughly" the number I should expect now?
2.) If not, what can I do to get the "right" quote?