Airtime depleted without any warning of Data bundle depletion

Good Day, My data bundle ran out on the 3rd of April and depleted almost all of my monthly airtime. I am on a uChoose Flexi 350. I received no sms alert that the bundle has run out or that I am now paying out of bundle rates.

The last sms alert I received was on the 27th of March wrt a data bundle being depleted. Why don't I receive alerts everytime, and only sometimes? It's these type of actions that make me frustrated.

Please contact me.

Regards, William