In case you missed it Google has a serious problem with Symantec SSL certificates and is removing their Greenbar status in Chrome as well as rolling out "not trusted" notices for sites using mis-issued certs by Symantec.
https://techcrunch.com/2017/03/27/google-is-fighting-with-symantec-over-encrypting-the-internet/
In response to the problems Namecheap is offering free replacement of the certificates - you get whatever time is left on your Symantec SSL certificate on a Comodo SSL for free.
https://www.namecheap.com/security/symantec-ssl-certificate-free-replacement.aspx