I'm not sponsored by the company, honest, and I have a history on here (Yoni massage, centre parks, poo troll etc) but I've just used this mould spray in my bathroom and OMG does it work!
I've had major black mould problems in my bathroom grout and was dubious that anything would shift it but bought this stuff on the recommendation of other MN-ers and sprayed it on earlier today.....and have been amazed by the results - seriously sparkling white grout - it changes colour before your eyes - you do not need to scrub or anything, just sponge the spray off after. Amazeballs! I seriously thought I was going to need the bathroom re-grouting before this.
Just had to share, for those who have a similar problem. 
It does smell so you need to ventilate well when you spray it on, and it does bleach so be careful (don't get it on your feet like I did stupidly standing in the bath while I sprayed it - realised just in time. Have clean feet now anyway!)
(Disclaimer - I know all about more ventilation needed - treat the cause of the mould etc etc but just not possible in my tiny north facing bathroom)