If you were barred for breaching the fair usage limits
http://48months.ie/boiler-plate/terms#18
then you are barred for the remainder of your current monthly membership. Buying a new membership does not prematurely terminate the current membership and the ban period. It will just "stack" to kick in when the current membership has run its course and expired.
Once the current membership and ban period has expired you may still need to log a support query asking 48 to lift the ban:
http://help.48months.ie/requests/new
Be aware that a second ban is for good - i.e. you are barred from the network on your current SIM/number for good.
Hope this helps.
