I am based for work in Singapore

I am based for work in Singapore. I recently changed the contract on my cell number *** on 14 May. I advised that as I work outside SA most of the time I make use of the WiFi calling function. The upgrade lady said this should not be a problem. To my dismay after the contract was upgraded I found both my wifi calling and international roaming had been deactivated. Despite calling daily this has not been resolved. I have parents in their 90's that I am unable to contact. I cannot do my banking as no longer receive otp as sms is not working. I need the same services I had prior to the upgrade as at no stage was I told the existing services would be deactivated if that was the case I would have the previously existed services as is instead of upgrading. I need this rectified as soon as possible. As my SA phone is not working due to the above problem please contact me on my Singapore number +*** or my email address ***