Rain Service Provider - no service at all! - Please help

Two years ago my fiance took out a month to month contract (cash) and cancelled it succesfully. Apparently there is a small amount outstanding and hê wants to settle it. I've sent a sms to 44663 (complaint to Rain) to enquire the amount the 2/6/2022. A mail was also sent to *** the 7/6/2022, with no response to date. Numerous times I've tried to phone Rain's call centre but no one answers the phone. My fiance does not have a email address, so I mailed them asking them to capture my email address on the system (also asked them to contact me directky on my cell so I can sort it out). I sent them his ID nr and the web service #*** to pick up His information on there system. NO RESPONSE TO DATE. They are the worst service provider! PLEASE HELP. Kiet