The pigeons and I think a moorhen have been grazing on my peas, which is rather annoying as they don't seem to be picking on anyone elses peas! Slugs love beans and will munch them down to ground level over night, stems and all! I don't know whether a rabbit would be that fussy and only eat the leaves, so I would blame the birds. Now my peas have carried on growing - now I have netted them, so I am hoping they will be find, but with your beans, I believe that if they have been munched beyond the growing point and beyond any leaves, just leaving a stump, I don't think there is any hope....I think....so I would say start again :-[, however, there is still loads of time for your beans - I have some only just in pots!