Actually, I've found that even though Bell (cellular) screws up the billing occasionally, and they often don't understand their own policies once you get them on the phone. I've been able to get them see things my way, eventually, every time (I've been with them for almost 7 years). Sometimes it took a two hour phone call, but they always made it right. In comparison, when I used Rogers as my cell provider I went through the same hoops but never, not a single time, got issues resolved to my satisfaction.
I still hate Bell though for the games they're playing here. With a license to raise prices for the wholesale customers as much as they like as long as they charge their retail customers the same, they likely don't care if they lose all their DSL customers. That way they won't be using the pesky VOIP and internet television services which are eating into their REALLY profitable businesses - satellite tv and POTS/long distance.