Losing of MB on cellphone

I have 2 reference nr's Which Vodacom gave me nl.00S7-7L28 (they did not reply to my request of itemised billing statement -) + Ref 00UW-WO44 -I saw on my cell phone how my data are decreasing by 20MB (using watchdog app ) when I query this no response and this is not the first time -- I am not serving the internet frequently because I am so aware that I only receive 200MB per month ..from what I understand from various customers of Vodacom this is normal practise to all . I think I gave them a fair chance to response to my problem since they stated to respond to my problem in 24 hours -- and isn't it strange that all the cell phones start giving software problems after one year such as freezing screens etc , which I also experience now .