depending on the actualcause of the problem - warranty job.
if its due to using powders, like Fintan says, its a possibility that Ashbys may not hold to the warranty even though its there powders.
As Aztec says, there are better ways to clean carpets then running powders or even liquid cleaners thro the pump.
Get a good quality sprayer, a stainless steel preferred (about £180 investment set against business for tax purposes), and use a liquid prespray or make 100% sure powder is fully disolved before putting into sprayer (mix it with really hot water in a jug to fully disolve it).
Better still use something like Nemesis or M_Power as your main cleaning agent, and have something stronger for the tough jobs - but either off those two will serve you well if you follow the instruction.