Adblue warning in my Q2

Hi

5 days ago when putting the key in to start my 2019 Q2 I got a message saying "1400 miles left put in 4.5 - 6.5 litres of adblue"...or somesuch. I duly bought some and added it on Sunday however it only took around 3 litres I'd say. I expected the warning to go out but each day this week when I have driven it, it hasn't.

I have now driven 2 x 60 mile+ trips in it today and thought that that might help but it didn't. I am still getting the same message however it is down to 1200 miles now!

Any ideas folks?

I cant be without the car as we live in a very rural location and my wife is disabled.

Cheers