Problem with updating to Piwik 2.15.0

When I try to automatically update, I get an error message as such:

curl_exec: SSL certificate problem: unable to get local issuer certificate. Hostname requested was: builds.piwik.org

I tried to do a manual update but the person who set up Piwik initially claims to have used a “simple, standard set up” and won’t provide any information regarding FTPing into the server to update manually. Is there anything I’m missing in this update equation (I must be!)

Cheers