Car finance help

I’ve got a bmw 330e on finance and it’s a great car but the running costs were higher than I realised the finance is 400 a month hp but all in I’m spending well over a grand a month and it just doesn’t seem that worth it to me, I’m wanting to swap to a mk8 golf gtd which is similar value to my car but it will be cheaper on my insurance,tax and fuel. How do I go about doing this what’s my best option with all the finance?