Hello,
I'm a vTiger developer and have 8+ years of experience with it, since vtiger 5.x version
I know vtiger 6.2 very well and can solve the issues with your Vtiger system right now.
Access via Cpanel is great.
About update, It's hard to quote before review your system.
I have some question:
-Do you have any customs module in your Vtiger?
-Do you have any customs code/functions in your Vtiger?
I'm waiting for your reply.
Regards,
Cuong Nguyen