Brittany Ferries Strike

I was due to travel Santander to Plymouth on 26th September with car and caravan. Due to the strike the   sailing was cancelled and I had to return Calais to Dover. This entailed about 1000 miles extra to my home. Brittany have offerred £200 fuel money. This is possibly reasonable for a solo car but my fuel cost was about £305 and tolls were about £130 plus extra site fees and the loss of four days holiday. Has anyone managed to persuade Brittany to pay more compensation?