I don’t think it’s a Peugeot Citroen issue, as others have pointed out, some companies charge a huge amount extra for heated seats as part of a pack.
Even in our top of the range XC40 Inscription, which comes with leather electric seats, heated seats were only available by specifying the Winter Pack.
This we did as Mrs 72 dudes also finds them a year round comfort for her spinal issues.
Do some more research. If heated seats are more important than the car itself, the top model Hyundai i10 has them as standard I believe. Otherwise it’s down to your choice whether you put down a larger AP.
Or leave the scheme and have a free choice of options which can be built into the monthly PCP payments.
Just few years ago it would be unheard of for cars in the Peugeot 208/ DS3 to have heated seats even as an option.
When choosing, we quite liked the DS7, but you couldn’t specify it with front parking sensors.
To us, that seemed daft, but instead of coming on the forum complaining, we took it off our list. Simples!