I was once using Vodafone because Qtel won't give me post paid till I have my QID. I had recently joined my company then.

My Sony Ericsson C905 phone's call history used to get erased every now and then, making things difficult for me. I called Vodafone's Tech Support and explained them this issue. They had no idea whatsoever.

I was pretty damn sure the network was causing this issue because I'd lose the Network access very frequently and after regaining the access, the call history would be gone.

Btw, loss of Network shouldn't erase your phone's call history. It never happened with Qtel and neither with Vodafone India.

After obtaining my QID, the first thing I did was switch to Qtel. I have been ever happy after that.