Useless Network provider

I have a contract package with MTN and before leaving the country i sincerely asked them to activate call and data roaming and they told me they did but when i got to australia the package is useless, i cant use the internet yet they are now deducting almost double of what i use to pay for a useless service. both my personal and business life is affected by this as i now how to rely on public wifi to do anything and whenever i enquire i am told my roaming is active… MTN does not disappoint when it comes to being useless the only thing they are good at is debiting our hard earned money.