Talk:Spain/@comment-213.143.46.175-20180102153426/@comment-24682153-20180106233029

Depends on your plan/tariff. With Vodafone Yu you can renew ahead of time anytime and get the new allowance for 28 days while unused allowances roll over (not when changing plans).

On Orange Mundo it's the same story without roll-over: http://www.simmundo.es/ayuda/consumo/. But there may be tariffs for which you can only buy add-ons.

Generally, it's cheaper to buy a larger package than to renew your plan all the time. There are providers selling packs of up to 25 GB or more.