I'm guessing these shattered because of shock or perhaps from being fully extended more than normal since the front wheel takes a lot of the weight when drawer is fully extended. The rail is acting as a lever where 10kg in the front of the drawer could easily be the equivalent of 100kg on that wheel when the drawer is fully open. The other thoughts are if someone where to lean on the drawer or if the cabinet was being moved and dropped.

I've seen replacement wheels, but they tend to be for specific rails/sliders, and I doubt you'd get a good result without a perfect match. For replacing the entire slider, I'd look for a replacement with a high weight limit. I've seen sliders in the US that are designed for 50kg, which I'm guessing would more than handle your load.

Hacksaw

Lots of work. BORING!

Oscillating multi-tool or Rotary tool

You're probably not cutting 1/8" steel with this, but it's useful for cutting very thin metal.

Jigsaw

A little more fun, but still a bit tedious. Make sure you use the proper blade.

Reciprocating saw

More fun, but you may have trouble keeping a straight line.

Angle grinder

Let the sparks fly! Lots of fun, and it will allow you to plunge cut.

Torch

An Oxy-Acetylene, or Plasma torch will make short work of this job.

Punch press

Finish the job with the press of a button.

Lightsaber

Fast, but requires a bit of Force.

If you're using any of the saws, make sure you use cutting fluid to prevent the blade from overheating.