Need help figuring out how to fix a representative payee mistake on my grandmas SSWB.

My grandma had been from nursing fac. to nursing fac. for the past 2 years due to no one in the family to care for her at home. One of these care centers was an assisted living. I have very limited info on what took place but when I heard that this place was mistreating her and she was begging to get out I came back to Cali from Texas to help. I took her from this place AMA in early March this year. I then took her to the hospital to be checked out and asked doctor to please recomend a skilled nursing fac. for her till I could make us a place to live suitable. She had a joint bank account where her widows benifits went direct deposit with her son being second party. there had been no disruptions of her benifits at all until May 3rd when her benifits just stopped coming into the account. My uncle tells me that the assisted living home was trying to get him to pay for her care and he refused to do so. So they had a doctor state that she was in capeable of managing her own affairs and took her down to the SSA office and made them selves the payee on her account. I am not sure when exactly this took place but like I said I removed her from the place in early march so had to be before then. It took 30 days for them to figure out she was no longer in their care and then they froze her benifits. I did not know any of what was going on till late may when she was coming home to stay with me at her old residence with her son. I took her down to SSA office as soon as she didn't recieve her april benifits into her account. They told me that they stopped her payments because they could not verify where she was and that she had to have a payee to get her benifits reinstated. she was right there with me and was able to answer all of the questions correctly that they asked her. She was a bit slow and hard to hear but she was still fresh out of the 2 years of misery she suffrered bieng in the institutions. The lady at the window was acting like we were trying to pull some kind of shady stuff. I demanded that my grandmother had gotten a clean bill of mental health by her doctor who was caring for her in the last skilled care facility that she had just been released from all in good standing to me as her caregiver. She needed 24 hr care because she was a fall victim NOT any mental condition. I asked them to please call that doctor or facility to confirm this..they refused. I told them that my grandmother was becoming very depressed losing all rights to make her own desicions so I was trying to give her her dignity as long as possible which was why i refused to accept that she needed to be assigned a payee. That acusation was made by the skilled nursing home in order to gain control of her account. They very rudely denied her this and said she had to have a payee no matter what any doctor said. I took her home and we tried to visit a different SSA office and they said they couldn't open her files they were locked by the other location. So by this time we were getting desperate to get her money started back and went back to the local office and spoke with another woman who helped us fill out the application to make me her payee. I had all id's and everything they needed, they made copies, we signed and she told me it would all be fixed and we would be notified by mail. 2 weeks later we recived a check for 1 month of due back pay to my grandmothers and my correct address but with the name of the person who had applied to be payee in the skilled nursing home. all the following paper work notifying us that this woman had been approved and was assigned as payee. That woman has never lived at this address. Nothing came saying I had been denied as per my application but it was very obvious that our visit to make me payee had resulted in this action. A VERY seriously CLEAR mistake on the part of the lady who with we spoke and made the changes. we got 2 more checks in her name I turned all of them into the office. This third visit I was assigned yet another clerk whom could not figure out any of what was going on, she said she couldn't tell who had made what changes on her account there was no way to trace it. (HUH?) She brought 3 different other clerks, managers etc over trying to trace who had done what. Then I asked her what about my application to be payee she said there was nothing on file . I dont know what they came up with but after an hour of trying to figure it all out she handed me a form to take home have my grandmother sign and a witness stating she wanted me to become payee bring it back and be fixed. I brought it back with my grandmother with me and got sent to talk with the first rude woman we saw the first time. she said I had been denied as payee because i failed to return some forms she had given me which was lie. It is completely clear they screwed up something very seriously and are trying to blame us, my gma is in dire need of her money its been 4 months already they refuse to help?