Can't complete patching process since patch 3.26.0j so unable to launch the game at all as a result.

Can't complete patching process and therefore play at all since patch 3.26.0j

Many people experience this issue. https://www.pathofexile.com/forum/view-thread/3869030 Seem to happen to people from Russia. Please, look into it and adress it asap, GGG.

I still need to finish challenges and I would love to practice before League start. :/

I'll help you faster and better than the entire support team: use a VPN

good luck with closing challenges