MTN pain in the butt

I am on pre-paid - have bought Airtime to the value of R400 over the past 10 days, received SMS's confirming that I have bought Airtime but it is not showing on my MTN App - in other words it is not available for me to buy voice or data on the app. I battle to get through to MTN today the last time the call centre person said MTN has a systems problem to reflect the payment for Airtime - now why can MTN manage every other message etc. but not to reflect my Airtime payments on my MTN App? Should I rather change to another service provider. Frustration is an understatement.