Seeking money for poor workman ship

Used Tiaans aircon to repair fridge, they did a amazing job. was told that i get a 3 Month warranty on the work done. Just after 3 months the fridge broke on the work that they have done. I have asked them to come back and redo the work and I have paid them for it since it was after the 3 Months, a month later the same problem and now they want to charge me again for the same work even dough the work is in the 3 month period and they want to chare a call out for the work and I'm just 5 Min away from them.