Sliding door cables

[KernowMPBen]

Hi, hoping someone might be able to advise on next steps! On 31st Dec my 2018 MP sliding door cables seemed to drop, becoming visible on the outside of the van, hanging down. After some research I can see this may have happened because the cold meant aged cable clips may have broken. I took the van to local dealer, who charged 200 for a diagnostic. The diagnostic included cutting and removing the cables (!). And a report that I needed the entire motor and cable unit replaced (at £1200). I have managed to negotiated a refund of the diagnostic - given that MB policy is always to replace the whole assembly. I’m now struggling to work out how to fix it myself, hopefully
By just replacing the cables. Has anyone done this, have any advise or know a garage in SW that might just replace cables rather than whole motor?

Thanks