Well, it's a complement in a way and you know there is a limit to how much you can do. Hopefully, they will give you credit for your map. If they have altered it and are taking the credit that would be upsetting.

Most people who are using your map are probably having fun with it and out of appreciation should give credit to you. This matters because it's like advertising and if someone else wants a map they can only look you up. That could be profitable. So they could be held liable. (A hassle to deal with though I'm sure)

If they are jerks I'd say post here and let us know what website it is so we can blackball them or at least go post on that website about how wrong it is that they are taking credit away from the artist. That should fire up their community and that pressure would I hope cause them to rethink their position. It would be a pretty stupid thing to ****off a community of artists because we have ways of making you look bad. How about a challenge that paints them in a bad light? Don't directly use their names of course so you can't be nailed for slander but you know what I mean..."Behold the Asslands where credit-denying map users reside." hehe

Fortunately most people seem willing to give credit where credit is due. And as long as I get credit people can find me. I would try to look at it like an advertising budget. You have to spend some to get more and as long as it's promoting your name it's probably good.

Ultimately you have to ask if it's worth your not doing any more maps. I figure I'm going to get used at some point if I'm good enough and sure, I'll be mad at first but hopefully all the folks here will be ready to help me calm down when and if it happens.