Default [Q] Anybody exploit the loopholes in AT&T billing?

Let's say you are on the 1gb $50 plan. You are 15 days into your bill cycle and used 900MB. You then switch to the 2GB $65 plan. You get full use of the new 2GB plan's data for the rest of the bill cycle. Yet you pay a prorated $50 bill and a prorated $65 bill. You get your 900MB and another 2GB of the new plan and you avoid the overage charge. Right after your bill cycle ends, you change it back to the 1GB plan and again and repeat as necessary. I just confirmed with the rep that you get the full use of the new plan's allowed data.

Upon more research, it seems AT&T backdate your plan change therefore you will be paying a full price for the new plan and leaving you with only 1.1 GB the rest of the cycle. If that is the case, I've been misinformed again by the bright people known as AT&T reps. So does AT&T still backdate the bill cycle or do they pro rate both plans for those that have tried it.

Upon even more research, I saw that Verizon will prorate both plans but calculates your data allowance daily. Meaning if you used 1GB in 15 days and you are on the 30 days 1GB plan and change your plan mid cycle, you will get hit with a 500MB overage charge, since you are only allowed 500MB in the 15 days period. So common advice was to backdate the higher plan to avoid overage charge. In conclusion, there is no loophole if this is how they calculate the prorated bill.

I heard AIO does not do that and allowed you to use the new plan's entire data allowances when you change plan.

In conclusion, ignore this thread. I was misinformed by the AT&T reps. The best way to avoid overage charge is to BACKDATE the new plan, otherwise you will likely incure an overage charge since that is calculated as a daily allowance.