Adblue light, low emission, engine light, service light

Adblue light on, along with engine light. Topped up adblue but no warning sign to say it was low at 1,500miles which it normally does. Taken it to two garages both have said there is nothing coming up on the computer apart from adblue low. ive put 10litres in it so it isn't low. I've done alot of research into this so has the garages and we have found a "common fault" the sensor is placed inside the tank so when that is faulty you have to replace the tank costing just under £1000 for the tank alone. My research and also the garage has found This is common in ds3 after 2-3years. This is no wear and tear on these cars it's a common fault. Why are paying customers being made to pay for a fault in the car? I also had a quick chat with a sales man who tried selling me a car rather than helping me with my problem and actually agreed that it is common and they don't know why citreon has decided to put the sensor inside the tank!! Answers are needed immediately by citreon!