Where can I find a simple plain black t-shirt?

Why is it so difficult? A few months ago in Primark I found a lovely t-shirt. Plain and black (required for work) short sleeves and long enough to cover my bum (which makes me more comfortable in my job) so I bought 3 of them. Recently my shifts have changed and I need to buy some more shirts, but I've moved to uni so I can't go to the same Primark.

I went to my new local one and couldn't find anything. I tried H&M, Debenhams, River Island, Topshop, New Look, Next... and I think that's it. They're all local to me. All the black t-shirts either have a sheer back, are far too low cut or have some writing or pattern or design on them making them not suitable.

Why is it so hard to find a simple t-shirt? I've found one on Asos but I'm having order troubles but if that gets sorted I'll be fine. Does anyone know any other stores I have missed that I can try? Or possibly online?

Go to primark again if not and one with a logo is fine nike or north face

I've been to Primark twice and it needs to be plain black, so no logos. Literally nothing but black cotton.

Primark always have plain coloured t-shirts