I have 3/4" plastic piping running along side my boiler as the main hot water feed before connecting to 1/2" to the radiators. I wanted to arrange a monthly maintainance plan & called Homeserve by Scottish Gas who sent someone out. They told me that they wouldn't take me on saying that I should have copper piping within 5ft of the boiler. The Boiler is a Modena 80E combi. Is this right? Do I now have to change the pipework?