Advice around benefits and housing- who do I contact?

Any advice please. I've just been to see Greg Clark my MP but getting nowhere! My husband died and I was paid a Sum of money 're death in service. I live in a housing assoc property and thought it wise to put my pot of money into a shared ownership  I met the criteria for HOLD (help to buy for folk with lifelong disabilities) I receive PIP high rate and needed to be in ESA support group. I needed to be put in support group to move my purchase forward and was in regular ESA group. I called DWP every week to be told no decision made yet. I called Medical Services directly as it seemed to be taking a long time (received ESA from beg Sept 2018) and Medical Services advised that my case was closed mid Nov, passed back to ESA although it was now mid Jan 2019! I lost the level living flat I was buying as the owner got fed up waiting for me and the decision from DWP 're me moving to support group. I received a call from DWP and was placed into the support group of ESA within the hour. This delay of information has cost me the chance to help myself with my housing dilemma, my one chance of securing my future in a disabled friendly flat. My benefits stopped altogether begJan 2019 as the sum I received was over 16k and I've now used 8k paying my rent/council tax/living costs. I don't object to the rules, but had the decision that I was placed into the ESA support group in Nov 18 been advised to me, the money would have gone into the shared ownership.Im now left in a 3 floor townhouse at £220 pw and very soon the country will pick up the tab of over 1k per month for rent and council tax alone, with me in a property that doesn't meet my needs! I need advice please with who to approach, surely the DWP are accountable to someone when they make an error? It's a life changing one for me! My life has been on hold for 6 months and I need to move on. Thanks.