Pip appeal won housing benefit refused

Hiya I won my pip appeal in September after a long 18 month wait to go to appeal .I was awarded standard daily living backdated to March 2018.
I wanted to ask for a revision to be done on my housing benefit and went to the council office yesterday as I should of been awarded it if my claim didn’t get stopped when I lost pip they have said to me that they can’t award it now as I have done that out of the one month timeframe after winning my appeal .Are they right I’m saying this they are telling me to apply for universal credit but if my pip didn’t get stopped I would of still been on housing benefit and they owe me about 2000 from March 18-now .Is there anything I can do about this I didn’t know about the one month timescale after winning my appeal in which to give them the information Tia

Thank you .
I spoke to them a couple of times on the phone and they did not mention I had to do it within 1 month unfortunately otherwise I would of .
They were supposed to be sending me form for my employer to fill in regarding wages so I was waiting on that but it never arrived .Thats great thanks for your help I will contact them