Increased billing after contract

On 2013-12-12 I took a telkom mobile contract.On 2015-12-08 I proceeded to upgrade my contract.Due to lack of stock I was given the device with a new number on 2015-12-28.On 2016-01-04 I received my bill which is now billing me for two contracts.The first contract which has since expired has doubled in fees although I no longer owe fees for a device.The data rate is higher than any supp**** by same service provider.I was on smartdata 2.5GB the total with device under contract was approx.R260.Telkom smartinternet 5GB month to month cost R199.I am being billed R505 for 2.5GB smartinternet.Have reported to telkom ref ***4.They don't respond as that would mean less income to them.