Failure to deliver

I app**** for a confirmation letter re:proof of change of surname in march 2017. I was told the process would take 3-5 months. I have been going up and down being sent from pillar to post. I had to redo this process 3 times because each time I went to check it didn't appear on the system. This is really frustrating because I cannot apply for any loans or finance due to the different surnames. I went for the 4th time today. This is very bad service