Incorrect Billing new Contract

I ordered a Huawei Pocket Router with Smart Internet Plan online on 11 September 2018. It was delivered to my 19 September 2018. I just received my first bill. Device Subscription Fee 01 Sep 18 - 30 Sep 18 R99.00 Smart Internet 500MB 20 Sep 18 - 30 Sep 18 R14.66

Why do they charge me the device Subscription from 1 September already. Why must I pay rental for a period of 20 Days if I only received the Device via courier on 19 September 2018. I do understand that first bill has a pro rata rentals but it should be from the date that I received the device. I did call your call center 081180 to log a dispute and the lady informed me sorry that is they way Telkom bill. I do not agree and I am very sorry that I ever trusted Telkom to sign a contract. I will warn people not to take out contracts with Telkom because they rob you from money.