upgrade available, when you want to upgrade u cant

I called the call centre every week for the last month to ask if i can upgrade my lines, i get told yes on the 7th of november you can upgrade, i sent an email 9days ago no response, i left messages no response, now when i phoned to upgrade i get told sorry the promotion ended and you cannot upgrade until december, NOBODY told me that it was a promotion that was runninh. NOBODY. i get told you can upgrade in december becuase there is a 5month promotion, whats the chance that i will call and get told SORRY promotion ended AGAIN. ive been a client for 4YEARS and EVERYTIME upgrades time i have ISSUES!!! YOU CANNOT RUN A PROMOTION AND THEN YOUR STAFF DOESNT ADVISE CLIENTS THAT IT IS A PROMOTION TO UPGRADE AND WHEN IT ENDS!!!