falsely declared in 2019

Guys I have a problem with the company I used to work for. i was declared in 2019 but I was no longer working for them. I then got retrench from my recent job so as I was applying for UIF my application was declined because of that mistakenly declared. when I go to them and ask for the letter of falsely declared they don't want to give me. now i want to sue them but I don't have lawyers. how do i go about that. please help Thank you