Cpanel server needing help to configure IP address and get emails working on server

I have a dedicated server hosted at OVH that I need help repairing. Problem started when additional IP addresses were removed by datacentre including one used by secondary nameserver. I now have new IP for secondary nameserver and have added it to server but needs configuring properly. At same we tried to upgrade cpanel to latest version which failed. Since then no emails on server are working. I have a ticket open with cpanel regarding upgrade but need to get emails working again.

The server hosts small businesses. Websites are still working on server.

Need someone reliable who is trustworthy.