Confusing staff/system

since last month I've been getting emails from telkom reminding me i can upgrade, So I saw this wonderful deal on facebook for a huawei pocket wifi for R99. thinking that its a great deal I went into one of the stores to apply for an upgrade, got great service from the store staff but I couldn't upgrade cause apparently the contract I have now can't be changed to the one I want, So I decided to call the call centre just to understand why this is a problem. So the lady said her manager told her I can't downgrade. Since when can't a client chose? what happened to the CPA? This is so confusing... I don't even use the number telkom gave me nor do i call with the sim. Lucky its only till may then I can close this chapter