How can I stop my cats soiling in the house?

What can I do to stop my cats going to toilet on carpets etc?

My cats are both indoor cats - they have a litter tray, which is cleaned daily.

However, for a long time now they seem to have been soiling various areas of our house and clothing.

I have tried food in those places and neutralising smell sprays and cleaning.

They are 11 years old. What can you suggest as this is getting expensive to replace carpets?