Ahh Channel 4 - they sure know how to offend people.
Complain by all means, but you may well end up even angrier. I did a couple of years ago at a programme they put out on a Sunday lunchtime with what I considered some quite adult sex scenes. I was angry as my little dd could very easily have seen them and it was inappropriate for the time of day. When they eventually got around to replying to my letter, it was poorly written, deliberatly failed to see the point I was making and ended along the lines of 'if you don't like it, switch it off..'
I don't know what's worse, the ignorance of some of their programmes or the 'couldn't give a s*' attitude if you say something about it.