Steps to reproduce 

Load into game.

Go to Dressing Room. 

Select character.

Choose Style

Choose Headwears.

Choose Axolotol hat by Tetrascape OR ANY of the Axolotol skin sets

Receive error "Sorry, we were unable to complete your purchase, Maybe check your internet connection?"

I Have tested this on two different accounts one for me and my daughter with different Operating system versions using the Minecraft for windows version.

i have tested off my network and past my firewall and through my Hotspot.  Issue persists on different networks, different PC's and different accounts.  Seems to be a system outage error of some kind.