I have an S3 mini and every day my text message ringtone rings at 9-00am and then again at 9-00pm

[AC Question]

On my S3 mini at 9-00am and 9-00pm every day my text message ringtone rings as though I have got a text message so I check my messages immediately and there is no new messages I have checked everything and still can't find out why this is happening could you help in any way please or any suggestions thanks