low gas pressure

Had a Vailliant 838 boiler fitted about 7 years ago by Etta via British Gas. It has been serviced every year by Etta. Last year it developed a fault after several visits by Etta and Vailliant, Vailliant refused to visit again saying the gas pressure was too low at the boiler and would not attend...

Hi, our gas boiler was moved when we had an extension built and the gas supply pipe is now at least 20m from the meter with many bends. It's time to replace the boiler but my plumber says the gas pressure at the boiler is way too low (I think he said 13?) and advises sorting this out before...