Free SIM activation forcing recurring goody bags and unjust enrichment to Giffgaff

A free simcard activation requires automatic subscription to a monthly £10 goody bag (which I was unaware of). We NEVER used the goodybag or simcard, and 7 months later, I realised the monthly purchase wasn't on my wife's giffgaff number, but on this (now lost) activated simcard.

I have conceded that it was my oversight not to read properly when activating the simcard, but giffgaff refunded only 3 months subscription, and cannot transfer any unused minutes or data on the previous 3 months to another number.

This incident in my view is unjust enrichment, and Giffgaff should provide at lease a warning if a client it not using a goodybag AT ALL, prior to renewing for the next month - 7 months in a row!