Misleading? Not really; you just didn't read it closely enough. <grin>
You should've asked your question before you bought...
You'll notice it didn't say 75B. The 75 (IPSC) Standard was a predecessor to the new Tactical Sport. If you visit the CZ-USA website you'll find the TS. All IPSC-type guns, no firing pin blocks (hence no "B" in the nomeclature) and all designed for IPSC competition.
I wouldn't really expect to fit 17 rounds into a mag for a gun originally designed to hold a maximum of 12 (10, really) rounds. Where are those 5 or 7 extra rounds going to go? It would take a wider mag to hold the extra rounds, and a longer one, too. None of these mags have a lot of wasted space in them, any more -- since the hi-cap ban went away.
But, look on the bright side of it -- if that's the only mistake you make in messing with guns, it'll be a cheap learning experience and well worth the money.
The 40B can generally use any 10 round .40 mag made for the 75B and EAA mags for the .41 AE round will work too -- but you may have to tweak the top rear of those mags.
These other mags won't look good in the 40B, cause it the 40B has an angled grip bottom, and 40B mags have a special baseplate to fill what would be a gap with a no-40B mag. The other mags will leave you with an unsightly gap. They'll still work, but won't look as pretty. (Unless you just buy some 40B baseplates, and install them... then you get extra rounds and good looks, too.)
I will be surprised if CZ-USA wil give you credit for the shipping and handling cost... They did their part and shipped what you ordered.