https://www.franckmuller.com/servicing/
http://www.harrington-hallworth.co.uk/servicing/ – check to see if they still are
https://www.prestigetimeservices.co....and-servicing/
https://watchesofdistinction.com
http://www.rebeccasjewellers.com/servicing-and-repair/
Frosts of London are also the only UK listed retailer, so ask them too, just for comparison, etc.
Being an ETA base caliber in most models, any good watchmaker/repairer should be able to handle them – our own member webwatchmaker (add .com for his website) shouldn’t have any difficulty, and might be able to obtain brand specific parts, if required.