So this issue only happen to FatPipe customers? Because I am on a gig4gig account and don't get this capped nonsense.
How I see it:
1. you used up this month's fatpipe data (since they use that first instead of the rolled over data)
2. you have bolt-on on this fatpipe account (which is not available anymore)
3. thus they cap you based on the fact that you did use up this month's allocated fatpipe data.
Only way this issue of yours will get fixed, if they change the usage model, eg. first use up the roll-over data then last this month's allocated fat pipe. Until then you will experience this issue you have right now. Or you should stay below the 50GB in a month.