Interest Rate decrease not app****

I have a home loan with SA HomeLoans. The recent decrease in the interest rates does not reflect on my monthly payment. When I phoned their call centre, they informed me that the changes in the interest rate is only done on a quarterly basis. I will only see the change at the end of this quarter. When the interest rates increase, it is app**** immediately. I have phoned them on the 4th of May and as I was not happy with the answer, I followed up with emails on the 4th and again on the 22nd. I had no response on my emails.