Has anyone had/have experience of 'Work Related Activity Group'?

I had my assessment a couple of weeks ago and they were quite satisfied that I was unfit to work, but now they have sent me a letter stating that they reviewed my notes and want me to attend a 'Work Related Activity Group'.
I find this very puzzling as my main problems are; travelling; especially to strange places and have to have my partner with me to do so, trust issues, which would obviously apply to strangers, being in a strange area that is out of comfort zone and being abandoned in that area.
Social problems which all result in Panic Attacks, crying obsessively and running away.
They told me that if I do not attend this program that they would 'cut me off' any Benefits that I am receiving.

Can someone tell me anything about this Program and any other information that could help me please?