Sorry to hear that.
To be fair when the roaming changes were introduced in June 48 did advise users to make sure to buy a Guido membership in good time in advance of traveling so that they could use calls/texts/data while abroad.
But I agree that it's a bit messy and it would be good if there was an option to force a new membership to start early.
In fact that would be to 48's benefit as they would be getting paid twice for the relevant period...