Missing php mbstring

Hi Dimitri.
I get the following error
The WHMCS WordPress Integration plugin requires the PHP mbstring extensions.
A couple of mbstrings are missing. http in and output as well as the detect one is not available. I have enabled .dll
I have a vps with godaddy. I have looked at different tutorials. I can't login with ssh as my server won't allow it. I have contacted cpanell, but I can't grant them access. Something to do with wheel group. Any suggestions as how I am going to solve this issue.
Thanks in advance for helping.