Return the stain Kit. You can use ascorbic acid. Here are two links to web sites:

http://www.chemistrystore.com/Ascorbic_Acid.htm

http://www.msm-msm.com/store/agora.c...scorbic%20Acid

You don't need the stain kit, if the vitamin c worked, because vitamin c is ascorbic acid. The pink stuff is a sequestering agent. If you want to get rid of the stain, the sequestering agent sometimes works if you lower the ph to 7 - 7.2 and add more than enough of what the bottle tells you to add. After a day or so if the stain doesn't lighten, then you would have to use the ascorbic acid, and I can tell you how to do that if you decide that is what you want to do. Keep us informed.