Honestly, look at the paperwork that you signed....if it says "O", I'd fight for the extra pay bump....IMO, they gave you a BS "excuse" for the pay increase and you have a valid argument....
On my last review, I already put in my 2 weeks notice, and I flat out told the TLthat I didn't agree with EX. I told them I busted my butt for Target for 9years and for the last 5 years and I was always given an EX because I was at cap pay unless I got an O, and given sub-standard training and supervision. But I don't care because I was I was leaving in a week.