You would need to start a web chat with Smarty support to switch to the 50GB for £8 offer.But obviously that will only be possible if that offer is still available once your 40GB for £5 offer comes to an end.
Assuming the email is legitimately from Smarty and not a scam (log in direct to your Smarty dashboard rather than clicking any links in the email, just to be safe) it sounds like it's telling you your registered payment card will expire soon (all cre...
This is most likely because your phone is not compatible with Smarty's VoLTE (4G calling). Previously, phones which are incompatible with Smarty's VoLTE will have been switching down to 3G to make or receive calls, but most of Smarty's 3G coverage ha...