Welcome to our Community and thanks so much for your first post - I was sorry to hear that you're having some issues with your Call Waiting on your mobile services. Whilst this feature is something that we can activate on your account; it will be done to the handset weather it will work or not.
I have located your account from your forum information so will pop you a quick Private Message so we can go through security with you. Once all done, we can activate and you can then activate from your handset and go from there.
Look out for the Purple Envelope in the top right of the page and pop me a reply when you can.
Thanks for your Private Messages - we can confirm that the feature is now active on your account from this end so you are more than welcome to attempt activating it from your handset now. You may need to reboot first.
As advised earlier, we cannot guarantee that the feature will work; it is handset dependent.