Student loan balance not going down on gov.uk?

On the gov website it says I’ve only made £1440 in repayments but this is so untrue as in December I received a bonus and I paid £1200 in one pay check in itself.

I’ve had this job for 17 months and each month about £225 comes out and goes to student loan repayments so I can’t believe it’s saying only £1440 I’ve repaid.

Is this just interest or surely somethings gone amiss here? Not to mention I had a job before this one that took about £150 out so I feel like my student loan is never going to decrease if it’s telling me I’ve not paid anything!

Call the repayments section and ask them for the total value of payments they have received from you.

I really recommend you read the following MSE article (or watch the video) explaining interest and loan repayments. It's not clear from your post if you made an additional voluntary payment when you received your bonus or if the amount was taken automatically. Unless you are a very high earner, there is usually no gain to making additional payments.

https://www.moneysavingexpert.com/students/repay-post-2012-student-loan/

No it was automatically taken!