Swapped car battery

I took my car in for a 30000km service on Friday the 4th May,they couldn't finish my car in time. I was aked to pick it up on the Monday all well and good I understood. To my surprise on Tuesday morning my car was not go on only to find out that they jad swapped my car battery for an old one which was not working. Amd they couldn't care less my car was working well before then