Won't receive my certificates

I joined a nursing home career as a resident aid a year ago as i'm writing this however i eventually quit due to harassment and unfairness taking place at the job. i put in my two weeks, but by the last week of my time there, i ended leaving because of the conflicts i was having with that place and couldn't mentally handle it anymore. when i worked there, i had given them my certificates for my first aid and cpr but never gotten them back. now my new job is requesting for me to show them my certificates since the state came and is doing a "survey" on the employees. i contacted my old job and they said they won't give me the documents because they paid for it.. when in reality i ended up using my own money to pay for my certificates because there was an error to the process and i had to redo my certificates and pay it my own and redo the classes. i don't understand if what they are saying is unfortunately true and they can't give me my documents, or if what they're saying isn't true at all and they are only saying that since when i left that week many were upset with me since staff that day struggled with the residents when i didn't show up.