You need to make a complaint and also get your MP involved, you will be surprised how fast things happen once a MP gets involved. It does seem a bit ridiculous having to involve your MP at such an early stage but the earlier you resolve the issue the less stressed it will get.
I contacted my daughter's MP and she contacted the DWP. They had sent my daughter a form to sign to give permission for me to act on her behalf. She had received it but hadn't opened the envelope (she often leaves mail unopened for weeks). I told her to find it and she did. She signed it and put it in the return envelope. Before she had a chance to post it she developed chest pains and a cough. She is self-isolating until April 4.