If I remember correctly, during the production process of Ibiza 6J different types of Xenon headlights were installed in it (maybe I'm wrong), and I also think I remember that one of the BCMs used for one of those Xenon headlight types is the BCM that you currently have installed. 6R0 937 088B (Re4).
Do a search on the net ... (Part No SW: 6R0 937 088 B HW: 6R0 937 088) ... maybe you will find some autoscan of a 6J with the xenon headlights installed, ... and the unit for the automatic headlight leveling.
I recommend that you contact iichel, he had a similar situation with his 6R "Bluemotion" ... and because I'm sure you will understand each other perfectly (NL).
The heated seats are highly recommended, it's a great upgrade.
Here is a link to the parts catalog in case you have to look for the parts you need, learn how to use it and everything will be fine for your upgrades.
viewtopic.php?p=466570#p466570
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Here is an example with a BCM 'F' later than model 'B' but in essence it is the same: (...with module/unit '55')
https://forums.ross-tech.com/index.php? ... ost-113148
Well, it's a very strange post, but it confirms my suspicions ...
By the way, I would have fixed that problem in 0,1 sec ... OEM way ... but I'm not registered on the ross-tech forum.