Direct debit not set and internet cut off without warning

My elderly mother started with Virgin last month and had broadband . Internet was not working this morning and after doing some digging and setting up the app for her it transpired she owed for last months internet and this ongoing month with a late charge and a charge for a non received paperless bill added in . 
My mum is adamant when she phoned and set up broadband , she would have set up the direct debit . There had been no email or contact from Virgin to say the internet would be cut off or payment was overdue . I paid it through her app that I set up for her  ( reluctantly in the case of the late payment charge and non received paperless bill charge) and have set up direct debit online . Tried to speak to a human voice to complain and get clarity as to what had happened ,  but got an automated payment request which the minimum amount to pay was £1 to get the internet back up . I did this so she has now paid the full bill plus this additional £1 . And 20 minutes later internet is back on 

My mother is elderly and all should have been sorted when the broadband was set up for her along with the contract . I do wish to complain she has been unfairly charged but want to know how to go about it plus get confirmation from now on she will be charged monthly via direct debit , how do I go about this ? 
thanks for reading