GP refused my deed poll

I signed my unenrolled deed poll the other day, have the required 2 witnesses and used the language on the government website. This is a legal document. I could have written it on a piece of loo roll and as long as I have the required signatures, it's a legal document.

My GP practice told me that the system they upload the deed poll to will not accept a document without an office name or a stamp. I showed the practice manager the government website which shows that my unenrolled deed poll is legal and that it's perfectly valid to make it myself, and he said that he would try, but that these self-made documents have been rejected by the system in the past.

I didn't get the name of the system but I imagine it's one that's common to all NHS GP practices. If some kind redditor could tell me if they know, I would like to complain.

My name is my name. By signing my deed poll along with the required witnesses, I have officially changed my name. And now my personal details on the NHS are incorrect and need to be corrected.