Hello Suzzy
I was absolutely appalled to read your email and feel very strongly that either you or your Mum should seek advice from the CAB or the ombudsman such as OFCOM or Otelo in order to resolve your problems satisfactorily. I can emphathise with your situation but you shouldn't be paying bills that your mother has not incurred and feel that this matter should be reported to your local CAB or Community Legal Advice Centre as a Social Policy issue as well. There is also another organisation called CISAS and you may be able to lodge a complaint here as well.
I hope you can regain the strength to contact the telephone ombudsman and resolve your outstanding issues promptly.
Good luck with any future endeavours.