Old Spice stick ruined all my shirts

Due to my active lifestyle I've had problems in the past finding an efficient antiperspirant. Old Spice stick worked really well! Then after two weeks or so I found that all my shirts have this solid patch in the arm pit area. After a few washes some of these patches even turned dark grey / black. We tried Vanish, baking soda, Windolene (haha) and even boiling water. Those areas are indestructible. I emailed their customer case and they called me from a spam number (embarrassing on their part) and offered me a R75 voucher. They never called again or tried to offer me an explanation. I'm really disappointed with their lack of "caring". The products works great, but your shirts will become useless after 2-4 weeks.