No need for apologizes guys (but thanks), as it wasn't your fault.
Hopefully, it'll wash-out. Naturally, I just did laundry yesterday, but I gotta wash it soon to see what happens.
I'll be writing them either way, but if it doesn't come clean, my message to them (after I get a refund) will be more unpleasant.
P.S. Too bad SpreadShirt folks didn't take more pride in their work, as their business model seems useful.