I don't think its a question of not being able to prove it, just compare like for like new business with existing customer renewals with the same criteria. eg compare a renewal quote with a new business online/telephone quote and see if they are the same, Easy enough. The real issue is whether they care to look for it and what are the penalties/fines and are they substantial enough to discourage companies from not following the rules.
We have just had our house policy renewal with an increase in rebuilding costs of 3.5% in the valuation and the premium has fallen nearly 20%.compared to last year.
