Dude…
Get on the phone, call them on this as it's not what was promised nor in the contract you signed!!! Easy Peasy…. Like many others are TRYING TO TELL YOU… Stand your ground as once you get here, you are sucked in to their way and have absolutely NO leverage.
I know you're excited about this new life and new career… as we all were but once you get here it will all change and you will see what we are all trying to nicely tell you.
I can only say to you… you should re read this entire thread and take seriously what those have said about standing your ground on this. I can't tell you enough about this!!
Re read this thread 3-6 months from now and read what we all tried to tell you. You will then and only then understand.
Best of luck to you and a warm and hearty welcome.
Kap