I've had trouble taking calls from ESA, what can I do? I also haven't heard back from PIP?

Please could somebody offer me some advice? I have been off work since December, I have supplied fit notes, I started getting esa on the 1st of Jan, I have also applied for pip on the 20th Jan, i received a letter saying I was due a medical assessment for wca over the phone 1st week in March sat by my phone 3 hrs nobody called, I then had another letter saying they were going to call last week for my assessment, same again nobody called, I rang wca, the chap said the hp had tried to call me 3 times last week, this is nonsense as I sat by my phone for 3 hours again, nobody called, he then suggested I had blocked numbers in my phone, no!! I don't have any blocked numbers!! So now what do I do? I'm still waiting and haven't heard anything? Also I have heard nothing from pip?