Put your offerings in writing not via a call center who cold calls 
My area is finally moving over to fiber, Telkom called to sell the fiber upgrade offer, while I agree in principle I asked for details as the person on the phone couldn't answer questions, I asked for this in writing, yet it seems that this is not an option for Telkom to put anything in writing, you say your recordings are proof, but this is of no use to me as the consumer. I want an email confirming an order not a verbal ( especially as I have since been called 3 more times with the same offer to upgrade ) put your offering in writing on an email to your customer, include detail like the FUP ( the website regarding FUP does not indicate anything useful , as a consumer I want to know my bandwidth will be throttled by x % or down to X speed when I reach X GB of downloads .  I should not have to call your sales line or visit your shops to get this information, it should be made available as a client, if I am expected to honor your contract I am entitled to a copy