Debt Recovery & Regulated Activities

Jagista

I've now had three cases in recent months where I've been taken to court over old credit card accounts. All the accounts / claimed debts are unenforceable due to the original creditor being unable to supply suitable evidence in response to my CCA requests. Two different DCA's have taken these cases to court when they are not regulated by the FCA to do so and its only due to being well supported that I've been able to fight these cases successfully with the claimed debts being dismissed, either due to a lack of evidence being supplied or the DCA and their solicitors not wishing to pursue the case once they realise their claim will be contested.
Does anyone know please who I can formally lodge a complaint against this practice with? I imagine it would not be the FCA as the two DCA's are not authorised by them in the first place? These agencies seem to rely on scaring people into paying them monies when they know they are not authorised to do so and apparently issue hundreds if not thousands of such claims every month. 
I'd welcome any thoughts as to what Authority I could raise a complaint against this practice!

Thanks.