I propose an idea that will make your customers happy, and won't hurt the wallet: Roll over data caps. That is, each month, any data left on the user's account will be transferred to the next month, and so forth. This should accumulate indefinately. So for instance, if someone is on a 40GB cap plan, and there is 1GB left at the end of the billing cycle, then the next month, the user has 41GB available. If they then only use 39GB again, the next month they will have 42GB available, etc, etc. Note that this doesn't just apply to purchased data packs (like some other ISPs have).
Now, this isn't a new idea, but I believe it's a very good one, and it's good for both ISP and customer. Normally the argument against this idea is that ISPs factor into thier prices the fact that not every customer will actually use their entire data cap each month. If they get to keep the left over data, the argument is that they will use it later, and hence end up actually using all the data they paid for (whereas normally they won't reach their cap every month).
I say this is a fallacy - most users (light users, who don't really pay attention to their caps anyway) won't do anything differently, only they will have less chance of a "bill shock" if they go over their cap accidentally, since they should have accumulated plenty of extra data cap. Heavier users, such as myself, will not necessarily use more data either - and when they do use their "extra" data, they won't use it all in one go. For example, we often have a few GB left over near the end of each month, so in the last few days, I attempt to use the data we've paid for by finding things to download that I might not have normally wanted enough. This results in heavy usage over a few days as opposed to spread out over the month. If caps rolled over, I wouldn't have to worry about that, and could use my data at any time (Not so peaky usage! ++ for you!), and wouldn't spend it on sometimes frivolous things, just to use my cap before the next cycle.
This will also have the nice side effect of rewarding long-term customers, as they are likely to have built up a large data cap, and not have to worry about going over near the end of the cycle. We've been with TelstraClear for 6 years, I think, and as far as I can tell, we're just as "rewarded" as any new customer that signs up today.
I hope you can see how beneficial this would be, and that you take it into consideration.
Comments?