Views on Severe Disability Premium on ESA

I was getting the Severe Disability Premium on ESA following a stroke after being made redundant September last year. My Mum was coming in daily to help me. However, she sadly had a stroke in October (whilst on holiday) so my friend moved in to my house to help. He took me back and forth to Norwich where my Mum was in hospital (I had not been given the all clear to drive at that point). I didn't get back home until January & I notified ESA that my friend had moved in. They immediately stopped my Severe Disability Premium. I asked why and they said it was because someone else was living at my house. I explained that we were not financial linked and he was not my carer. He was simply staying at my house until the situation changed. I was then called in for a very intimidating interview and have now been told I must pay back the Severe Disability Premium from October to January. It seems that the Severe Disability Premium has nothing to do with severe disability, but is in fact a Single Person Premium. I would have no issue if that was the case, but I am furious because I still have the disability but am £256 per month worse off. It seems that through a friend doing me a good turn I am the one to suffer. Surely this can't be right in this day and age? (Sadly I know it is!) I can't help feeling we should all be complaining loudly that a payment called Severe Disability Payment is actually nothing to do with disability. I'd be interested in other people's views on this.

Thank you Gordon for your helpful reply. I appreciate I have lost it because my friend moved in, but my annoyance is because it is called a Severe Disability Premium but is in fact a single person premium. Personally I feel we should be challenging that kind of language as it implies a benefit that is related to the disability, but that is clearly not the case. The lady I spoke to at ESA told me it wouldn't matter if I was in a shared house with unrelated strangers as I would still have lost it. That is clearly not a disability premium as unrelated strangers have no responsibility towards their fellow sharers in a shared house.

Actually, I live in a shared house with unrelated strangers, and I get it. We all have separate tenancy agreements with the landlord.