Ive been in my new job 2 mnths but the emplyers are not very good, they keep messing up my hours and wages?

i am still waiting for payslips as the benefits office have asked for 5 to prove my hours as i do 16 hrs a week to claim working tax credit but so far i havent had a payslip and beneifts office can cut tax credits without proof. the company i work for has given most of staff wrong wages all underpaid and so my payslip if i ever get them will show ive done less hours than i have how can i get around this problem? they owe me money