Website needs reinstating

General information for the website: Property rental consultancy
Kind of development: Customization of existing website
Num. of web pages/modules: 10?
Description of every page/module: My website www.rentfacilitator is presently down
The web hosters (Media72) tell me that it is because it is : 'using Ruby on Rails version 2.3 which is over 5 years old, we no longer support websites running versions of Ruby on Rails that are so old, the current version is 4.1 and supported versions are (3.1, 3.2, 4.0 & 4.1). I would recommend that you upgrade your websites software so that it uses the latest version of Ruby on Rails.'

I therefore need the site upgrading.

I am happy with the 'look' of the website - however I will also need a few alterations (for instance a banner removing, telephone number changing, changes to the text on a few pages). But can only give these changes once the site is back live.

Could it be also possible for me to get control of the admin sysytem for the website? I have other sites where I have access to do the changes myself, and this is so much better.
Description of requirements/features: see above
CMS and Admin requirements: see above
Specific technologies required: ruby on rails
Extra notes: