First you should ask the company for references from an online service such as Checkatrade, her you will be able to see what other consumers have said about the company. You will also see their ratings, for service, workmanship, tidiness, and cost. Compare them with other service providers, check to see how many customers have left a review, a company that has over 100 reviews should be a quality company to use. Call them and check their prices, the average cost for getting a carpet cleaning London, should be about £150 pounds including VAT. A single size lounge should be in the region of £45 and a thru lounge about £65. You get a better deal if you go for a 3 bedroom house cleaned as they should have have a package deal. Getting other services like upholstery cleaning and mattresses cleaned, should be asked when booking in. Ask about the booking times they offer, including Saturdays and Sundays, The weekend are premium times, so you may have to book well in advance to get an appointment that suits you. Once the cleaning has been done, you can opt to get them Scotchguarded, this will protect you carpets or upholstery from future staining, and make it easier to clean in the future. Cost for this should be about 50% of the overall cleaning cost.
Check what equipment they use, a truckmounted system is the preferred choice, as this will leave the carpets dry, enabling you to use the rooms in a shorter period. You should always check that your carpets or upholstery can be wet cleaned, otherwise this can result in shrinkage.