Disappearing data

DISAPPEARING DATA!

On 19 Nov at 00:38 my iPhone showed I had NO data. At 09:15 I bought data on my bank app and my phone showed 458.90 MB. Buying R55 (460 MB) usually lasts me about two/three weeks. At this time I was at home with my WiFi working and I was NOT using my data. On 26 November I had NO DATA so I bought 1.25 GB at 08:42. On Saturday 29th at 07:28 I had NO DATA left. On Sunday 30th I bought 420 MB. BY 18:00 on Sunday I had 142.41 MB. AT 18:04 I was down to 16:44 MB. ALL THIS WHILST I WAS AT HOME IN MY WIFI ZONE! At 18:07 I received a message saying I was out of bundle. I bought R55 - 420 MB at 21:43. When I checked immediately- one SECOND later at 21:44 I had 389.97 MB! Monday 09:46 it was down to 404.03 MB. Monday 20:01 it was UP to 417.41 MB. CAN YOU EXPLAIN THIS?!? Tuesday 11:15 it was 400.86 MB. AT 19:27 it was UP to 410.38 MB.

By this time I had changed almost all my data usage on various Apps to OFF.

I have NEVER used this amount of data, even when all my Apps were running. Something very strange happening here. Is there an explanation before I change my service provider?