You should be able to check if they are valid.Just log into your account. If they are valid, the total minutes/data of those gifts/purchases should add up to what you have remaining
What type of add-on do you have? If you still have data (check your account, and use the refresh button to refresh the stats), then you can ignore the text message.If you're getting log-in errors, try using a different browser or using Incognito mode...
