You should continue to benefit from this each month when your data refreshes on a 4G tariff. You will receive a text saying your rollover has been removed. This is because you can only keep it for 30 days extra (i.e. 60 days in total).
In other words the maximum you can have at any one time is 2 months' worth of your tariff.
For example, if you use 2GB in your first month of the 4GB plan, the remaining 2GB will rollover giving you 6GB to use the next month.
If you only use 1GB the next month, you won't carry the full 5GB remaining over, but just the 4GB from that months' tariff.
You'd therefore have 8GB of allowances for the next month... and so on.
I hope this makes sense, but let me know if I can still help out .
I received the same this morning - the first text says "... you've kept your unused data from last month...", then 15 minutes later second text says "OK, we've now removed Data Rollover 200Mb from your package. ...."
The first text was nice to receive, the second text message is at best confusing, at worst annoying or misleading. It could alpost certainly be worded better - or not sent at all.
The rollover thing is very misleading and not explained properly. I signed up for 300mb data sim only at £6.00/mth and been told that I can rollover and accumulate any unused data. When I call 789 at the beginning of each month to check my data availability I am told I have 300 mins of unlimited text and 299mb of data. I hardly use more than 50mb each month and so it does't look like my unused data have been rolled over every month.