misled into paying too much for your buy to let property?

Access

i received a letter from a firm of wilmslow based solicitors on the above subject.
the giste of letter was that certain surveyors rountinely supplied inaccurate valuations to popular developers such as Challenor, Instant access, Dylan Harvey and Dandara which misled buyers.
the solicitors are looking to investigate such purchases with a view to claiming professional negligence on the part of the surveyors.
they are seeking £1K per case to undertake a survey and a their basic fees. if they win they take 25% of the reecovered monies which they say can typically be £40K.
has anyone got any experience of this or similar service?
kind regards