I was called by my future supervisor yesterday morning telling me that they are going to be making an offer. But it's a large corporation and the HR dept has to call and give me the official offer. 

HR called an hour later and made the offer. Approx $15k more than what I originally asked for. She said it's based on number of years of service and the person hiring me put 14 years - which is correct. She said she'd email a link to the offer and I needed to respond by the end of the day. When I got the email about 10 minutes later, the link wouldn't work. It said the offer had been rescinded.

I immediately emailed HR and got no response. A few hours later I called HR. She gave me a vague answer that my years of experience need to be adjusted and that she was alerted by the person who hired me to rescind it until they could clairfy. She kept insisting that it wouldn't be a huge reduction but that it wouldn't be what she just quoted me. She never called back yesterday. 

I'm wondering how to respond today if they call and say they are reducing. I know they will say that it's still within my desired range but I'm a little miffed that no one even bothered to call me and say the offer was being rescinded. I'll also be a little miffed if they say they aren't giving me full credit for all years -they are all relevant to the job. 

What would you do? Go along with it because it's still in my desired range or tell them that I'm not taking it because if this is their practices for just giving an offer, what happens when there are other issues down the line? Thoughts?