Good service with a small glitch. Review on NTL Calltaxi

I have travelled in many call taxi services and to be frank they are almost the same. The tarrifs are same, the condition of cars are  same, the availability, punctuality, driver politeness and service offered are almost identical. I stick to NTL call taxi because I had been a regular customer I never faced any discomfort with their services. I have written this review to convey an important point.

When ever the NTL call center guy offers any discounts or something the driver  doesn't have a clue. Some drivers say they don't know any and some out rightly deny any discount. Only after calling back the NTL customer center any discount was acknowledged by the drivers. My question is why is this happening? Does NTL leaves any offers under the vigilance of the customer or there is lack of education and information to its drivers? Anyway NTL should rectify this issue double time.

Any discounts and offers should be displayed on the meter and billing machine stuffs in their cars else NTL should never claim such offers and concentrate on regular service alone.