Add-ons are explained here:
http://www.48months.ie/membership-plans/add-ons
They provide mobile minutes, landline minutes, texts or data if you have used up your membership allowances before the membership month is up and the membership expires or if your membership does not provide an allowance for the relevant service (in particular data).
There are also add-ons for EU roaming calls/texts:
http://www.48months.ie/membership-plans/going-abroad
Note that if you use up membership allowances before the membership month is up then buying a new membership will not help as the new membership will simply "stack" to kick in when the current membership runs its full monthly course and expires.
It is not possible to terminate a membership early even if allowances have been used up.
You can check your add-on allowances and balances using your online My48 page (https://www.48months.ie/my-48), the 48 Android/iOS app (http://community.48months.ie/t5/The-Newsroom/My-48-iPhone-app-now-available/td-p/23615 ) or using these short codes:
Handy short-codes
Note that there are no add-ons for things like calls to non standard landlines (e.g. 1850/1890 etc.), MMS messages, international calls and incoming/outgoing calls and outgoing texts while roaming (other than the EU roaming add-ons mentioned above) and all of these are charged to your cash credit balance (if any).
http://www.48months.ie/membership-plans/other-call-charges
http://www.48months.ie/membership-plans/international-calls
Hope this helps.
