I actually received a short reply from them today by email. Basically what it said was you can only get miles ONCE from each opportunity - then they listed the last 5 I completed and showed me where I had completed them before - up to 5 months ago! They send them out again, with the same instructions - but if you completed them before you don't get anything - I guess we have to remember every one we've already done.... I responded back to them but I can't repeat it here...