Poor after sales service

I took delivery of a LDV on the 30th November 2017 and was given a licence permit for the vehicle. unknown to me one is not permitted to use a LDV commercially with temporary plates. on several occasions now we have contacted the sales person regarding the registration plates, he never comes back to us and always blames the licencing department. If ever you need to buy a vehicle which needs to be used commercially, a...don't use THRIFTY CAR SALES and b...don't pay and take delivery before the vehicle is fully registered.