i second quinnos post, if you are not confident at making a neat job of the silicone then ask the tiler in a nice way if he will come and take a look at it, have a tube of white silicone at the ready, chances are hell say its not my fault but if you ask him he will probably run the silicone in for you,you might consider offering money to him when he turns up, if he's any good he wont take the money. reason = pr for him, you will recommend him for future work!
Regards,
Steve