Need to get website to the latest PHP Currently Version 5.3.29

I am looking for a freelancer with vast experience that can undertake the task of reviewing my current site. I am told it is out of date and cannot be upgraded. All that can be done is it started from brand new essentially doing each page again I am made to understand. I cannot trust just anyone to do this it took years to update each stage to it bit by bit. It is essential that nothing is overlooked and someone who understands the task well undertakes the role. I have a development company but their time to do this task is very long as it is many man hours they inform to me. The website is unlockingsmart.co.uk and there are many areas to it including back panel access. There will need to be a clear agreement and understanding in place before anything can be agreed for certain.