Housing benefit overpayment from 2014

Bsmelly01

So I received a letter from housing benefit today telling me I didn't declare that I worked for the council between 2014 and 2015 and i was overpaid housing benefit. This was a casual job but i did inform them. I remember handing in my bank statements as I always do. This was a difficult year as I split from my husband in the September. They are asking me to send all details of household income for the whole year within a month. As it was joint with ex til September this isn't possible. I don't have access to these bank statements anymore. I also found a letter from benefits section from February 2015 asking for 2 months bank statements and wage slips. The council wages were paid into my bank account so surely even if I didn't inform them (I know I did) they would have picked the extra income it up on the bank statements? They have put something about underlying entitlement which I can't do as I don't have access to evidence for the whole period. Any ideas what I can Do? Why wait this long?

IAmWales

Duplicate post.