I cannot get the tea stains out of one of my mug sets. I can only assume it has something to do with the type of china - my mum bought them for us a few years ago and I think they're from the Royal Horticultural Society or something. The tea stains are driving me insane. I would resort to bleech, but DP would leave me! . any thoughts? Have tried lemon juice, boiling water, and bicarb in various combinations with no success. TIA