Fridge regas and repair onsite on Gumtree- No gaurentee for their service

Found "Fridge regas and repair onsite" on Gumtree using contact no *** and they came onsite fixed and regased my fridge. A month later the fridge required a regas again. When I called Monday they said they would come Wednesday but did not. Thursday they never took any of my calls even though they advertise "Our workmanship is guaranteed."