How can we get the landlord to clean up the mold in our apartment?

This is the third time we've called maintenance to come fix the mold problem in our apartment. Everytime time it rains heavy.. water seeps into our closet under the carpet. You can feel your socks soaking up the water when you walk in the closet. They always respond quickly but never fix the problem permanently. They've changed the carper, cleaned the mold but they're not fixing the root of the problem because it cost to much. What can we do as tenants to make them fix this? The smell of mold is unbearable.