Weber on top of K-Rend

Hi all,

I am a HO and am currently having some rendering work done to my mid-terraced house. We kept the old sand and cement render underneath but had all the bad knocked off. On the front our renderer's used Weber.pral M and we are happy with it. On the back they used a K-Rend. We weren't aware that they were using a different product until it was applied and was a completely different colour to the Weber. Now we've asked them to redo the back in-line with the front and think they are planning to put a new layer of Weber over the K-Rend. So 3 layers of render on the back wall in total. I'm concerned about this but am unsure of what issues may arise, whether any warranties would be void etc. Should they knock off the K-Rend or go ahead and re-render over it?? Seeking expert unbias opinion :)
Their suppliers told them it would be a direct colour match (now we have one brown wall and one grey :-/). The Weber Sil P sounds like the simplest option - would it just be directly applied to the K-rend or does the K-rend need to be treated with anything first? Many thanks for the advice!
just paint it with weber sil p job done
He said he was worried about his warranty.

No way ether K Rend or Weber would look at a wall with both their products on. Weber sil p ain't warranted on K rend and K rend would wash their hands of any wall of theirs with it on.
I spoke to Weber who also suggested to paint the K Rend wall with the Weber Sil P, so that's what we've gone for. Not an ideal situation but seems to be best option to me. I know my warranty will be shot for the K Rend so best I can get is a contractors guarantee. And surely a discount off the original quote!