A strong spray of water - perhaps with a little soft soap or washing up liquid in it (just a drop!) - might help on the basil. The problem is that the leaves are delicate and bruise easily. Try, but be gentle.

We also only grow basil in the greenhouse and indoors. It is very tender and doesn't like changing temperatures. It has been quite cold at night through August down here (as low as 8 degrees) which they would not be happy about.