Unexpected payment from tax credit questions please help

[Supervet]

Unexpected payment of around £500 gone into my account around a week after renewal.
Can't get through on the phone to ask why.
Tweeted the HMRCcustomers Twitter who said if I've just renewed it is a one off payment generated from that and don't panic it's just that.

My income wasn't any different so I'm comfused on that one .

If it is a mistake can they take it from my account directly or will they take it from my next tax credits?

Keep ringing, you may be waiting to get through for an hour but eventually you'll be able to speak to a human.

If you are worried that it's an overpayment, don't spend it until you have confirmation from them.

It will be your final payment for last year. In my experience it's always been fine. There will be a letter in the post in the next day or two to confirm your final figures and new figures for the new year.