Busily prepping for first trip away and systematically checking everything and the sink suddenly won't drain. So off to get a drain plunger but any suggestions will be received with thanks. We don't put fat down the sink and it appeared to drain ok yesterday. I am not a fan of the drain buster products as I am not clear on what damage they could do. This is a 8 month old Rapido so I am a bit perplexed! Any suggestions gratefully received!