Website owners are being charged up to 30 times too much for work to improve their Google rankings, according to one Manchester-based search engine optimisation provider.

Colin Bell, operations director of Modern World Media, said he knew of one case in which an advertising agency quoted £25,000 to carry out a three-month test contract for a Manchester-based healthcare provider. The client shopped around and got the work done for £850.

Bell said such cases of “scandalous overcharging” were creating a mistrust of the industry, which he believes should have a higher degree of self-regulation.

“Many clients do not know how much they should be paying and they are being taken advantage of in some cases,” said Bell, who set up the Albion Wharf-based company with brothers Simon and Piers Vaughan in October.

It provides a white label service to other marketing agencies as well as working directly for clients.

Bell said: “Search is unregulated, there’s no governing body and pricing is very varied because a guy working from home can have the same or more skill as a big agency in Manchester or London, but his costs would be vastly different.”

Mindy Gofton, head of search at I-Com International, based in Manchester, said she was not aware of similar cases of overcharging but added: “I would guess that it probably has happened. You are going to find huge disparities in what companies are charging and what they are offering.”

Gofton said a more common problem was that clients sign up to cheap deals from SEO companies only to find they did not deliver what was promised.

Some SEO firms use so-called “black hat” SEO to trick search engines, using white-on-white text or microsites to direct users to the client’s website. But this is considered unethical and can backfire badly.

“It can work in the short term, but if Google catches you, you are going to get your website banned,” Gofton said. “You should be careful of anyone who says it will cost less than £500 to get your traffic up 400 per cent. If it sounds too good to be true, it probably is.

“Most of the good SEO firms will charge an hourly rate or a package. They should be clear about what they are going to achieve, such as an improvement in rankings, and increase in visitors or conversions.”