You can do it on your own without voiding warranty, afaik. It is user replaceable, unlike Xbox. Like many others have stated before me, any 2.5 inch SATA SSD should work. Here's a video to know how to replace the drive:.
Thanks mate, for the response. Yeah, been meaning to get a replacement fan. Still dunno what to do for the broken blu ray flex cable. Kinda need it since I can't really afford paying for digital games atm.