Originally Posted by
jarusoba
AC.com won't give you M and U fares, unless all lower Tango+ fares are sold out.
Call them, use EF or KVS to find out how much.
Then call AC to book.
For those like me who are to cheap to pay for EF or KVS, you can search on
http://matrix.itasoftware.com
Origin: YWG :: /f bc=m
Destination: LHR :: /f bc=m
If you type in the above for origin/destination, you'll get all the M fares between YWG and LHR with pricing/availability.