georgestewart but the fact is
it’s all to late as the money has already gone from your account
But, usually, one is informed by text that one has (been) subscribed to a service and that a FREE trial period ends at a stated time. Instructions are given on how to unsubscribe. Also included is a, goodybag inclusive, number to call which can be used to unsubscribe.
Did you not get the opportunity to unsubscribe before funds were taken?
To clarify, subsequent texts are not Premium Rate texts. They are receipts for a subscription taken.
But all that said, it is a cause for concern that paying for such services does not require one to opt in with giffgaff as it does with some other providers.
EDIT to correct typos.