Altech Netstar
Not crediting double debit as promised

I recently purchased a new vehicle and had a new installation done.
The agent I spoke to, Keegan Govender, assured me in writing that I would be credited should a double debit occur. Now Netstar are not responding to my request. I verified this twice with the agent regarding the credit if a double debit occured, and even tho I forwarded his e-mail to Netstar, they wont credit me.