1. Ring Betfair customer services and ask for your lifetime profit/loss on multiples - they will send you a spreadsheet, not very detailed, though
2. Go to My account - Account Statement - from the drop menu choose 'sports betting only' - then tick 'multiple bets' . it gives you last 3 months only, not detailed too
HTH
There are 2 ways to find out :1. Ring Betfair customer services and ask for your lifetime profit/loss on multiples - they will send you a spreadsheet, not very detailed, though2. Go to My account - Account Statement - from the drop menu choose 'sport