It's a waste of time complaining. The whole worldwide motor industry is suffering from a massive chip shortage. A modern car can need as many as 3000 microprocessors to work. Many companies have had to close down production lines including companies like Mercedes. Mercedes admit that they have no idea when they are going to be available. One of the reasons is that the phone market takes 10x as many chips as the car market. Apple have just ordered 100 million main processors for the iPhone 13 for delivery in the autumn. Some manufactures are building the car and putting it into storage until the parts arrive and that have no idea when that will be.
Some manufacturers are putting what chips they have in there most expensive models, so, the chip for your Ateca is probably in a £100k Porsche.
SEAT UK are very unlikely to have the slightest idea when individual cars will be delivered, even if they are showing as having been built.
If you are desperate to get an Ateca your best bet is to buy a good used one and the prices of those are going up fast. My son agreed to buy a Range Rover demo model 2 months ago. He is still waiting for it as they cannot get delivery of a replacement demo car.