Can a job refuse to give me PTO that was pre approved?

I requested vacation for August 6-8, three weeks prior to that date as per my company's policy. However due to extenuating circumstances, I had to send a resignation letter on August 7th that my last day of work would be August 10th. I also added to the letter that I could be flexible with those days due to the company not having enough people who work the same time as me. However I received a letter today that's addressed for August 14th. It says I submitted a notice on August 4th and my last day worked was August 3rd which is false. I'm concerned that they aren't going to honor the three days I had for vacation by not paying me for them. If this occurs what are my options? Especially since that was pre-approved vacation time so technically my last day worked should be August 8th.