Is it possible to have Apple update RAM in current Mac mini (Late 2014) Is it possible to send my Mac mini (current version) back to Apple and get them fit more RAM into it? 

With the old models i could add RAM into them, but as I understand on the new current model Mac minis it's not user upgradeable.
Short answer:  No.

Apple is not going to retrofit memory into any Mac (Mac mini, MacBook, etc.) if you want to upgrade.  They don't even make simple repairs to their logic boards - they will just replace them.   

If you require more memory, you will need to 


replace the logic board
purchase an entirely new unit


While I typically would purchase a machine (Apple, Dell, Lenovo, etc.) with the highest CPU and lowest memory and drive specs, this has now become impossible since RAM is now commonly soldered on and in the case of Apple, their SSDs are proprietary.

Buy the machine with the specs you think you will need in the future, not for what you need now.