When I order over the net, it is MY responsibility to check that you have recieved my order, and to see if there are any issues. If I don't get off my behind and do this, then caveat emptor.
I purchased some printed T Shirts on line, and when I checked my order email, the seller wanted to know if I would accept another colour or wait 2- 3 weeks. It was a gift, so i chose another colour. If I hadn't checked, I would have waited, and been frustrated.
I think you did the right thing - it is a simple seam to sew it back to one big piece if that is what they wanted.
Thanks for asking us, and giving us the opportunity to talk about these things.