I am a little embarrassed to even admit this. I have NEVER had a washing machine incident - no shrinking or anything. But last week I somehow managed to put my new white shirt in with a denim skirt. My white shirt is now pale blue . I've put it in on another wash with one of those sachets of whitening things but it hasn't worked. What else can I try? The shirt is a polyester blend in case that makes any difference?
Try Dylon Colour Run. I have used this successfully in the past. My dear late MiL decided to do my washing once when we were away on holiday. My toddler son's new red shorts were among the other things. MiL didn't know they had not been washed before, consequently everything pale in colour came out pink. Colour run restored them to normal. Keep your blouse wet though, as, if I remember correctly it will not work if the garment has been allowed to dry.
Reminds me of an incident when we had a young newly married couple staying with us, until they found a place of their own. She put a load of her husband's new white underclothes into our washer, and must have mistakenly included something dark green. The "whites" all came out peppermint green - poor lass! I can't remember what she did about it, but they're still together.