MTN online is a ****

I recently bought an online purchase with MTN online only to discover when the router was not functioning within the the 10day period that they cannot help...I went in store and I was turned away telling me to courier it back but the debit order still goes off from MTN....it's a ripe off how to I dispute this on my TransUnion am paying for something that was cancelled and no provider wants to take responsibility it's day light ****.