Why is CVrecords limited to 250 API calls per day, regardless of version

Why is CVrecords limited to 250 API calls per day, regardless of version

We are a Zoho Professional subscriber trying to link Campaign Monitor subscriptions to Zoho leads. We have already gotten Zapier, our connection service, to reduce call frequency to every 30 minutes. Why is the Zoho API limit only 250 for CVRecords requests... the only type of request we actually use?

When will this be increased?