Terribly sorry that you have not received your cheque yet. I'll try and find out what I can but in the mean time could you check what address we hold for you here - https://www.giffgaff.com/profile/details#address
I don't have access to your account and it might be best to contact the agents about this as they would know better than I if this cheque has been sent to you.
Can you make contact with us on this email - firstname.lastname@example.org
UPDATE - 06 Feb 2019 - 09:11
Hi all, I have a short update for you on this.
Since putting in the fix, we’ve set up a series of procedures to make sure that we’re keeping a close eye on our systems and making sure that issues like this are picked up quickly and resolved. As part of this, we have regular meetings with our suppliers to understand changes that are planned to their systems or have been carried out, and their effects.
At one of those meetings last week, we discovered that a change that had been made in one of those systems had inadvertently allowed this issue to happen again for a short time. This was quickly addressed and was affecting members for under 48 hours.
Between 11:16am on January 23rd 2019 and 17:35pm on January 24th 2019, the fix that we put in place for this billing issue was not effective. That means that some members who bought a goodybag during this time, were using mobile data at the time, and continued using that mobile data session, would have been charged from their airtime credit instead of the goodybag that they had bought.
We’ve identified the members who were affected and we’ll be sending them a text message to let them know. Over 80% of members affected by this will be due under £1.00 credit refunded to their account. We’ll be refunding the amount that was erroneously charged from credit back to their account directly.
We are also continuing to refund members who were affected by the issue in mid-2018. The majority of refunds have already been provided, but there are some people who have since left giffgaff and that we haven’t yet been able to get in touch with because we’re not certain that we have the right details for them - for example, if they have left giffgaff a significant amount of time ago and may have moved. We will be sending out letters shortly to those addresses to ask people to confirm who they are and make sure they get their refund.
We’ll update again once all of these messages have been sent out to everyone - please let us know if you have any more questions.