Sounds as though it has been overwatered and has rotted off. Check and see if the compost is too soggy, although if the stems are mushy it's probably already too late and it will need to be consigned to the compost heap. What a shame! This plant doesn't need to be too wet, despite the 'aquatica' part of it's name (the 'specific epithet' if you're into gardening terms!!).

Hi,

Thank you very much for the advise, i have been leaving the watering up to my husband!!!!

I thinik i may try to re pot it with new soil etc and see how it goes if not like you said to the compost heap very annoyed as i do love my plant.

Thanks again