Get online support
Unless you logged into what you thought was TPG from a link in the email (never do that), and if you have logged in inependently and it shows as a credit on your account then it must be genuine. eg NBN credits are usually weeks after a problem. Odd amount though...
@Kdubbs Please send us a PM with your details and we'll look into this.
The email is definitely legit, @Kdubbs. Send us a private message and we'll check out why you got that credit.