Overcharging

I'm very disappointed with Telkom, they were overcharging me for a wifi router. They told me it's because I made a subscription for games?? I never made any subscription for games. I went into one of the Telkom branches and they saw the error. They said they would correct the error and refund me, but they still haven't refunded me. They keep giving me the run around. It's been approximately over 8 months that they have been overcharging me.