Logic fridge freezer model LFC50W12; problem with drip tray

Drip tray seems to get clogged and iced up in the tube at the back of the machine;;;mechanic came ; the tube is ‘frozen’ and has to be steam blasted; mechanic
says this seems to be a ‘common problem’ with frost free fridges; am advised to give it a very hot/boiling water treatment every few months to keep it uniced with a generous amount (300 mls) of boiling water ( or as near as dam it ) to keep it ‘flowing ‘; is this issue ‘common fault’ etc with Frost free machines; all my previous ones have been frost so how a frost free one behaves is a new experience !!