Indian Railways
Non-refund and increment in the waitlist status of ticket

I have reserved a ticket from dda to ndls which has booking status of wl28 and on 5th may its status is rac66 but on the day of journey its status is wl57. how can the waitlist increased and i have not got the refund till today. please consider my case as early as possible. my pnr no. is 6327094628.