legs 11

hi i to recived a letter asking about working tax credit 2012 2013 iv tryed phoning many times each time just ovrt 1 hr waiting then phone cutts offf I dont know what i was doing that far back letter says its a reveiw and check that it has number of hrs worked last know andress amount £2000 is this what they owe me or i owe them sorry but iam confused why they need to know when its now 2024