Our company has multiple domain names, all registered with one registrar. Our DNS on the other hand is being managed by Rackspace under our old web development firm's reseller account.
We have now changed our web hosting to a new host and pretty much our business relationship with this old web dev firm is terminated except for DNS. We still have to go through them when we need to make any public DNS changes.
What do you think is the best way to handle migrating our DNS account off of their hands and putting it back under our control with minimal hassle and service disruption?