Billed for a device I dont have

please assist as I have been desperately trying to sort this query out for the past month but to no avail, I received a new router from Telkom direct at the beginning of October, the device was faulty and I was told to take it into a Telkom store. I went into the lakeside mall store and my router was booked in, a few weeks later the repair centre sent a message saying the device will be sent back to the store in 4 days. After 4 days I went into the store and was told that I needed to wait for an sms or phone call from the store and only then will I get the device back, I followed up with the store again a week later and was told the same thing, I then went back and asked them to please check for the device which they done and when the lady brought it out and checked it she told me that they sent the device back without the cables and she will have to rebook it. its been 3 weeks now and I haven't heard anything from Telkom but I received an invoice for R446.84. PLEASE ENSURE THAT THIS DOES NOT GO OFF MY ACCOUNT AS I REFUSE TO PAY FOR A DEVICE I NEVER HAD DUE TO YOUR NEGLIGENCE! I expect someone to call me back ASAP and I want confirmation that this will not go off my account!