NOT UPDATING SURNAME

In the beginning of March, I asked for my surname to be changed to MY MARRIED SURNAME - I needed the updated Statement as soon as possible however after going through to different departments because I desperately needed this updated, I was told to wait until April's Statement so after waiting patiently for Aprils Statement it STILL has not been updated! I phone the call Centre and they say I must wait until May - I NEED this statement ASAP with my updated Surname that I requested last month!! This needs to be rectified ASAP!