After a very disappointing customer services experience with Three, who I'd been with for some years without any other issues, I shopped around for an alternative SIM deal and found SMARTY, I wish I hadn't.
I signed up for a SIM at £10pm for 4GB data and unlimited texts and minutes and money back for unused data in any month. SMARTY is a wholly owned subsidiary of Three and thus use their network though operate separately, just like NOW TV and Sky.
The SIM activation and number porting process went wrong from the start. The SIM wouldn't activate, the full instructions were not on the Activation web page and I was told porting my number would take a minimum of 2 business days, probably 3. When I ported to Three some time ago it was completed in half a day. A useless customer services agent named Callum tried and failed to assist.
After getting a bad feeling about the process I decided to quit, remain with Three and continue shopping for an alternative so I tod Callum to stop everything. He said he did but he actually didn't. He continued to port my number yet erased me as a customer thus leaving me without any 'phone service!
Rachael at SMARTY tried to fix the mess, unsuccessfully then, disastrously, Gary stepped in. He provided a PAC number for me to move my 'phone number back to Three or wherever else I decided. being in need of 'phone service I went back to Three, who actually gave me a better deal as a new customer!!
Using the PAC provided by SMARTY proved to be a nightmare as it was a bogus PAC which caused no end of problems at Three. Finally, nearly a week later (despite the best, or possibly worst, intentions of inept call centre customer services agents at Three) after talking with Claire at Three, she diagnosed the issue and sorted it out within 10 minutes and Three gave me generous credit on my account for my frustration.
Based on my experience, AVOID SMARTY!