Appliances 24/7 Not Reliable when it comes to Guarantees made

I had a call out for my fridge with this company number 0712718903, they fixed it, I payed as per details provided and advised a 1 year guarantee and to call if any issues..Fast forward i called as my fridge still has problems im told to come have a look at it a call out would be applicable, i send pop for payment that was made as they are now looking for an invoice they never issued. even my pop seems not to be valid. bottom line this company cannot be trusted to keep their word on a guarantee issued by them.