Ljubo, this is why I mentioned that you can always update manually. Until a couple of years ago, there was not comfort update and a lot of people managed to update. ComfortUpdate does what its name says, it makes updating more comfortable. But that's about it. The price is reasonable, but I can understand that costs can add up. Thus, there is still the manual update and it is no rocket science.
It is explained here:
manual.limesurvey.org/upgrading_from_a_previous_version
As said, those external installers seem to be a good idea, but usually cause more problems than they solve. Actually, installing LS has become fairly easy with a relatively simple process. I do have Cpanel installed on my VPS as well, but I always try to install without these one click installation packages, because you never know what they actually do with the software (they might change it, etc).