As it would be me replacing the fan for my brother i am wondering how difficult it would be. I am capable of building pc`s but have never had to open up a psu. As my brother said above his pc really is his lifeline so a possible rma taking up to a few weeks is a sore point and at £150+ they are not excactly cheap to replace either.
if you replace the fan yourself i can tell you, i did the same for my TX-750v2, (and the HX1050 uses the same stock fan, Yate Loon D14BH-12), the noise difference is night and day, if you RMA it you'll get back the same noisy stock yate loon
the stock one is a yate loon 140mm fan with 140cfm airflow at full whack,
I replaced it with a 140mm akasa S-Flow Viper with 110cfm.
Slightly lower airflow but still plenty for the supply, according to the manufactures websites the yate loon is 49dB at full speed whereas the akasa is 26dB, hence the huge noise reduction
I made it more difficult for myself by getting a PWM fan as the psu fan is only a 2 pin so i had to rewire the fan connecter, but theres nothing to stop you buying a 2 pin fan so its just a straight swap if you dont feel comfortable with that.
only drawback as mentioned is voiding your warranty, which is less or more of an issue depending how long you have left. (i think he HX are 7 years? whereas mine was only 5 )