The following are some tips and comments about donating old duvets and bedding – from Facebook groups:
Most animal rescues will take them usually.
The homeless shelter down near Cork bus station still take them as far as I know.
Simon Community Nicholas House Cove Street, Cork will take them. I usually ring beforehand to make sure they are there.
Try Cork Penny Dinners.
Dogs Aid in Finglas
Dogs Trust used to take them.
Try the UCD Veterinary Hospital 017166002
Try People Helping Homeless Group.
Try the freecycles if you haven’t tried yet.