alabastron Hi there. There might be an app on your phone using more data than it should? Maybe take a look at this which.co.uk article for details on how to monitor data use on your smartphone.
Also… Apps running in the background and/or updating via mobile data might have used your data balance (on top of your known usage). To prevent this from happening in the future, please make sure that within your Apps Store settings, you select the option for Apps to update using WiFi only. Furthermore, it’s probably best to switch mobile data off when you don’t need it.
Using an iPhone or a phone that has a ‘WiFi Assist’ feature? If you are using an iPhone or a phone that has a ‘WiFi Assist’ feature, please switch off the Wi-Fi Assist feature, as this uses a Wi-Fi/Mobile Data combination to increase data speeds, even if mobile data is switched off. If you are using an iPhone, please see the official Apple instructions for full details on how to switch WiFi Assist off.
However… If none of the above apply to you and you believe that your data balance is incorrect, please raise an an agent case and they’ll look into this for you. It can take up to 24 hours for a giffgaff agent to reply.
When a giffgaff Agent responds to your enquiry, you will receive your reply within your dashboard’s message section.