Billed R600 with the option to pay it over 12 months

Before I start my rant I would like to mention that I received very good service from Valerie Esterhuizen throughout the process. Telkom sent me an email 13 November 2017 at 14:23 giving me the option to upgrade (thoughtful of them since I have been buying extra data monthly, I was on a 30 Gig Contract) in the middle of my contract. The email clearly states and I quote "you now have the opportunity to upgrade to a higher data plan, without any cancellation fees, device fees or change in your contract period". To my dismay I am now being billed R600 device fee, when in the email I was told this would not be the case. I found the upgrade attractive because I would not be billed these fees. I feel manipulated and *******, Valerie had tried everything from her side, but did not succeed in having the device fee waivered. I would like Telkom to honour there email and waiver this R600 device fee as a matter of principle.