I myself have been a customer of many mobile network companies over the years with bad experiences with some and good experiences with others. I was first with T-Mobile when I got my very first phone and I was with them for a while until I switched to O2 and then I switched to Three and then finally to GiffGaff. I was with GiffGaff for around 11 years if not longer until my Mum told me about a new network called Smarty that offers a great service at cheaper prices than I was paying for with GiffGaff. I switched to Smarty in November 2022 and I have not looked back since. Their service has been great and their deals for a monthly package are amazing and are now saving me a little every month. The one company I would never go back to though is Three as I had a bad experience with them myself. 

Which mobile network company would you avoid?