Thank you for reviewing my idea, here it is:
Every month is different, sometimes I will go over my data usage or sometimes I will barely use data. This is also relevant to my calling minutes, sometimes I will go over or be way under my limit. Since I am paying for this un-used data and these un-used minutes I feel like the data and minutes that are remaining should be added to the next months plan. For example if I only used 200 MB out of 250 MB I would have and extra 50 MB for the next month. And the same for calling minutes.