Retrieving credits

Hello, my 6 year old son is a huge fan of this game. He got it in March and now has 76 cars :slight_smile: but today I saw he had a message in his ‘center’ so, of course, I wanted to see it (being he is so little I watch to make sure no one is trying to chat with him) but I opened it and it says he has 1280 credits to retrieve. But I’m wondering where they came from and why, when I click on it I get the message ’ Fauled to retrieve credits from server. Try again later’. We waited a few hours and tried again but keep getting the same message. Does anyone have any tips on this? Thanks in advance!