I'm afraid I've got a complaint., I'm sorry, but I've got a problem., I think there's something wrong with…, Excuse me, my … isn't working, Could you help me?, Could you ask someone to fix it?, Could I speak to the manager, please?, Would you mind fixing it, please?, I'm sorry, this will never happen again., I'm afraid there isn't much we can do about it., I'm sorry, we'll try to not make that mistake again., We are sorry, but there is no mistake.