Switching payg packs

[Someonelse]

I have a payg £15/25gb pack that renews later this month. I have more than enough data, so I’m wondering if I can switch to a £10/8gb pack and will it still rollover my existing unused data? Or do I lose my unused data if I switch to a differently priced payg pack?

[XRaySpeX]

Buy the £10 pack now & it will be held pending until your existing pack expires. You'll still get data rollover into it from the old pack. 

[Someonelse]

Thanks. I’ve since read somewhere that rollover works only for one month when I switch from a higher to a lower value pack. So if I have 20gb left it’ll rollover this month into the £10/8gb to give me 28gb but the following month, if I had, say, 15gb left, it would rollover a max of 8gb into the following month’s £10/8gb pack to give me 16gb total for that month. Am I right?

[XRaySpeX · Accepted solution]

Vaguely. Rollover works every month that you start a new pack within 7 days of the old 1 expiring. Only left over data from the pack itself can be rolled over. Previously rolled over isn't rolled over for a 2nd time.