Warranty or not warranty

[SeapangBlue]

I purchased my low mileage approved 2015my SQ5 TDi in September 2015 and in keeping with all my previous cars, from at least 2000, I keep a spreadsheet showing statistics like MPG and running costs.
Around February to March this year my monthly MPG dropped from 28 to around 14 with no difference in style of driving or local routes covered, as a retired soon to be octogenarian DV, most of my driving is urban with only the occasional longer trip.
I then did a further test MPG over a two week period and recorded 15 MPG, at this stage I contacted my local Audi dealer, where I purchased the car and they gave me a date of five weeks hence to bring the car in for investigation. During that time I continued to use the car which drove as normal with no display messages etc.
Just prior to them collecting the car I had noticed when checking the engine oil level it always showed a message to reduce the level, this info I gave the dealer in a cover note along with a printout of the spreadsheet.
They confirmed that there was a surplus of fluid in the sump and sent a sample of for test. This returned an above average mix of diesel in the engine oil. They concluded that the car had been going into a continuous regeneration cycle to clear the Diesel Particulate Filter which was never completed as the engine was never getting hot enough. I was unaware of this happening and made no attempt to clear the filter by going on an extended fast run.
At this stage the dealer informed me that Audi UK would not cover the cost of a warranty claim as there was nothing wrong with the car as I was not driving it properly. As a gesture of good will my dealer covered the cost of draining the sump and replacing the engine oil TWICE, once to flush any remaining diesel from the sump etc. and secondly to bring it back to normal capacity, they said they would not cover any future recurrence. In discussion with my dealer they suggested “the possibility of a petrol vehicle being more suitable to the customers journey habits to rule out the continuation of the problem”
What do the forum members think of the situation I now find myself in after spending £44K on a car that I really like but shouldn’t have bought!

[zollaf]

so they sold you a car that was unsuitable for your needs ?? is this what they are saying ??

[AK88]

surely the temperature has hit the midpoint on the gauge during your journeys? just take it for a quick blast once a week and that should avoid any reoccurrence,