From a newspaper...
http://www.telegraph.co.uk/property/propertyadvice/jeffhowell/7760467/Home-improvements-heating-system-powerflush.html
Unfortunately British Gas engineers have developed a reputation among readers for often recommending a powerflush, without necessarily having proved that one is required. Many readers have reported that – having paid extra for a powerflush – they have then found that it has not improved the performance of their central heating, and that other faults have later been found to be the problem.
I have been cautioning Sunday Telegraph readers since 2000 that British Gas engineers are given financial incentives to sell boilers, and other “chargeable extras”, such as the powerflush. British Gas has consistently denied that this is the case.
Follow link & read article...
Good luck...
Peccavi, January 2013