dettol mould and mildew killer spray about £2.50 from any supermarket.
thing is you can clean mould off, btu unless you KILL it it'll come back.
however, test on a bit first cos i dont know if it belaches. it';s designed for tiles, so i dont think they worried about that when they designed it. also helps remove the mouldy smell.
failing that, Cillit Bang (or the lidl version Adrit for half the price). that's pretty good stuff and doesnt bleach AS MUCH, btu again, try it forst!
good luck mate.