Sorry to hear! My previous car was an X1 xLine 25d but the standard seats were very poor and flat and hard. SO the first thing i did was to spec `Sports Seats and Lumbar. The sport seats were a bit more comfortable and gave better support whilst cornering. However, overall they were still not great overall and too small (I’m only 5ft 11) leading to back pain/sciatica over longer drives.
Now I’ve got Tiguan R-Line with bigger seats and more comfortable.
My advice is to first to read up online to adjust your seat and driving position initially as that could be the problem.
If not, then don’t waste time and contact Motability to get this car cancelled. However, I’m not sure you will recoup the £1000 for the paid extras. Just ring them and see what they say innit?