Thank you.... This is really bad. Someone should have told us.

Hi, - case in hand - older sister who is now over the age of 25 and claims I.S and low rate DLA. A few weeks ago we received our yearly rent statement (now changed to quarterly) and it shows us down in arrears by £740. Estranged I phoned up our landlord who told us that the rent has not been paid in full for the last year. I phoned the housing benefit department and I was told that my older sister now has to pay £15 a week towards the rent because she receives I.S. I asked why and was told that it is due to her now being over the age of 25. (she is now 26.) Is this really the case with people who receive I.S and reach the age of 25? It's the first time I have ever heard this. If not, who do I turn to for help? Thanks!