jasondavies9178 in the past couple of years giffgaff have tended to review their goodybag range twice a year. The last review was in February 2020 and before that, August 2019. So, there might be a review due fairly soon. As you can see from the post above, giffgaff are currently trialing a new £10 golden recurring bag. If it’s successful I would think they might extend it to other bags in the range, maybe even the smaller bags?
P.s. if it’s of any interest the Moneysaving Expert website has a couple of good deals at Lebara, £5 for 2GB, and, £7.99 for 8GB