Replaced Battery with a incorrect battery.

For me it was actually a bad experience with GM Le Roux motors. I took my car for a battery replacement (Chevrolet Captiva diesel). It was with Le Roux motors for 2 days. They told me that they are struggling to get a new battery. After the two days they informed me that my car is ready and that I can come and collect the car. After collection I arrived home I saw the replaced battery was only a 62 Ah and took up only about half the space of the correct battery and it is not a 90 Ah battery. The next day I phoned them and told them that this was not the right battery. The workshop manager then phoned me back and informed me that they did find the right battery. I went back and for the replacement and when I came there the battery was again incorrect. It now was a 66 Ah battery. They informed me that this is the replacement. I told them that I'm not happy and I want a new correct battery. I then waited an hour for the correct battery to be delivered. I now want to know how they service my vehicle if they don't know their own specifications.