Caller unable to leave a message when call is not

Cell phone was upgraded in March, since then callers are not able to leave a message if call is not answered. the caller gets the following message ''the number you have dialed is incorrect, please check the number and dial again\ <br> I have now spent hours on the phone with the call centre to try to resolve. On 16 July I called the call centre at 9h46 and was cut off twice. Eventeually at 10h17 I managed to speak to a consultant who transfered the call to 1555