Q: My computer updates to OSX10.6.8 and does not allow 10.8.5 which I need for Ipad/itunes access

You will have to buy a newer computer or learn how to use your device in a limited fashion without iTunes.  There are no workarounds other than learning other methods to transfer items.

The only way to avoid this kind of thing is to never update anything or buy anything new without first checking system requirements for every component involved and how that will in turn affect other components. It is one of the reasons why I have never purchased an iPod.  I would have to buy a new computer.  As a general rule of thumb, once any part of your system becomes more than 5 years old (maybe as little as 3 years for i-devices) you will encounter this kind of thing.  Your operating system is about 6 years old now.

It is not uncommon. I am trapped into buying a new car because I cannot find parts for my 35 year old model.

I notice now you use the term "update". There is a different between upgrade and update. Are you sure you cannot upgrade?

Software update, upgrade--what's the difference? - http://support.apple.com/kb/HT1444

OS X: Updating OS X and Mac App Store apps - http://support.apple.com/kb/HT1338

Reference releases; update vs. upgrade