You either do it yourself* (or get someone to do it for your) or take a risk with Sim Lim.
But with what they'll charge you, you're better off getting a new phone, from a reputable manufacturer this time.
* It takes some considerable skill and manual dexterity. I've replaced touchscreen glass, digitizers, soldered switches back on, replaced power switches, etc. Some devices are simple to repair (remove cover, pry part connector), some will have your remove everything just to access one part, while others will require pointing and waving a heat gun at the device just to melt some glue. Some just involves plugging and using tweezers, others will have you using a really fine soldering iron tip and non-shaky hands. It all takes some considerable risk.
"A quokka is what would happen if there was an anime about kangaroos."