Fenlake Car and Van Sales

We purchased a car from Fenlake some 3 weeks ago.  We had a test drive there didn't appear to be any issues, that day noticed the brakes juddering, we contacted Fenlake by email the next day to let them know.  So far Jay has done nothing. We were also told by telephone and email that the car came with 6 month warranty, and would be serviced.  Despite chasing, we are still waiting to see the warranty paperwork as for the service I was slightly dubious now if it had even been carried out, guess what it hasn't.  The oil is black and gritty, their air filter is full of bugs, not sure about the oil filter but I guess what, it hasn't.  We gave Jay (Fenlake) till 24th March before we took further action. We will contact finance company, trading standards, credit card company and lastly county court to get this matter resolved.