APR

Hi All self builders and developers, I am a property developer and need to change the connection in one of my property from 1 phase into 3 phase. I got a quote from UKPN with 3 options A - they do all, B-they do some and C- they do only the non-contestable works. At the field their engineer warmly suggested that it would be much cheaper to do the works with what they call ICP (Independent Connection Providers). Did anyone in this forum did something like this and can help me at to my next steps (as I have never did this before and don't know how to take it forward)? Many thanks :))