common charge refund?

I moved in my flat 1 & half years ago and paid an amount of common charges every month. The total sum is 300euro more than other tenants paid each month, as I thought it's provisional....
However, I have been waiting for the common charge breakdown list from My landlord for around 1 and half years, he told me he is still waiting for the syndic as well. I think he might not want to refund me the extra money after paying the common charge.
What should I do? Our contract said this should be given every year.
Please if anyone can help advice?