NEED ADVICE

I've been on esa for the past 5 years and on 73.10 a week. Didn't have a work assessment until February this year they told me I was fit for work. So I done the mandatory appeal or whatever it's called waiting to hear back from them... Someone mentioned to me that I could possibly get backdated as I wasn't put in a group and should be getting more money that what I was on? Not sure about any of this can anyone advise me