sounds like caterpillar or sawfly or slug/snail damage. what shrubs are they?

you could lift them and plant in pots and keep them and see if they re-leaf this year or in the spring.

Are the plants in question Box, if so then Box eating caterpillar could be the cause, this is a huge problem, they can defoliate plants very quickly, or as mentioned sawfly, these too can strip plants, however don’t be too hasty in taking out plants, in my experience they do come back, eg Berberis sawfly caterpillars will completely defoliate the plant but I have observed on many occasions they always leaf up well, some years are worse than others, try bark scrapes to check the plant is still healthy.

Thanks to seaburn girl, and julienne you are saying the same and speaking to my neighbour just now and she’s got box hedges all round her garden and they are the same.she asked a garden centre person and they said , yes it’s a caterpillar and don’t rush to dig them up.
Thankyou both