Broad Bean plants looking poor - with pics

[Two_Sheds]

As you can see from the photos, I have some serious problems!

It looks brown/rusty to me, not black. It's chocolate spot, mine had it really bad this year too

[Two_Sheds]

bean weevils whihc lay their eggs in the bean seed and then eat their way out, leaving a rounded hole

Nope, they don't. The weevil lays her eggs on the soil, and the grubs eat the roots.

It's the bruchid (bruchus) beetle that makes the holes in the seed

It may seem pedantic, but you don't want to be using a particular treatment or regime to deal with a pest, when it isn't that pest at all