Thank you for the additional information.
I apologise for the delayed response, I was away from the system.
Based on the information provided, as well as the university's regulation, it is apparent that you have exhausted their internal appeals process and there are no options left for you through the university to challenge their decision. I unfortunately am not privy to what was submitted to them to comment on whether you had set out in detail the basis on which the challenge was being raised.
That notwithstanding, I would strongly recommend that you seek to make an external complaint via the Office of the Independent Adjudicator. Please see below link with further information as to their complaint's procedure:
There mandate includes complaints including matters to do with examination procedures or simply procedural irregularity.
They are able to make practical solutions to a complaint. Some of which include, but is not limited to recommending that the school should
offer a fresh assessment opportunity
re-mark work following a different/correct procedure
give you the opportunity to redo the course
I do hope I have sufficiently answered your query . I would be grateful for your rating at this stage by clicking on the row of green stars at the top of the screen. Feel free to send me your follow on questions after your rating, if you still require clarification, I will still be able to respond to you.