Yeah

We bought some of that spray its about as useless as a chocolate fireguard ;D

We also tried some crystals from a car boot sale also useless!! :-/

We tried the fly traps sold in Sol D Ebre Agricol, they attracted million of flies and made things worse >:(

If there was solution that worked effectively, the makers would be millionaires Rodney

Netting off is the only solution or getting your neighbours to stop spraying pig and chicken slurry on their land, which incidently is illegal, if they spray manure it has to be turned into the soil immediately which non of them do of course!! ::)