I was about to leave spark as their data plans for my mobile were less than I could get from other providers. Then rollover data finally started. I had a conversation with spark and agreed to stay as they would give me 1gig of bonus data each month for the next 12 months.

In my head, I though, great, I might use about 1.5G a month so should expect to see the rolled over data grow quickly.

It hasn't

I looked at my usage yesterday,  My rollover data had used about 400Mb and my bonus data had used none.  the roll over data was going to expire in 10 days and the bonus data was going to expire in 16 days (this bit appears to be important)

My expectation was that any bonus data would be used first, then my rollover data, then any rolled over data that I had banked.

The way they do it means I will never use my bonus data up in a month. The AD man who thought this up must have been smiling "lets make it look like we are giving them something, when actually we are not"

a quote from the chat with spark:

00:29:40 ***** : thanks for waiting there. I've just checked your plan and your bonus data extra, and the way that it works is that the data gets used in order of expiry. Your plan data is due to rollover first, so it gets used first, and then the bonus data would get used. I'm just checking to see how that would work when the rollover accumulation hasn't reached maximum though.

I am waiting for an explaination as to why they think it should work this way.