OK so, finally, tried to download to PC and got "network error" messages after about 30% download. Repeated and same result.
Tried with iPod Touch and got "you have already downloaded this item, to download again go to "your downloaded items""
it wasn't there, surprise surprise
Tried to access it on the Cloud with the iPad and FINALLY I've managed to get a copy.
Hope it will turn out to have been worth it