Disgusting Service!!!

I am totally disgusted at Supersonic's service. My Husband passed away last year, our WIFI with Supersonic was on his name. I phoned the customer care services to change the banking details for the debit order and contact details as I wanted to continue with the service. I received an SMS to confirm that this has been done. Today I switched on my late Husband's phone and there is a statement from Supersonic for R1995.02. I phoned the customer care services to inquire how this could possibly be as the package I am on is R399.00 per month. I was told that they have not invoiced me for 4 months resulting in the account to be in arrears by R1596.00 and with April's payment the outstanding amount of R1995.02. I do not check my debit orders monthly, I trust that all my accounts are up to date. It is NOT my fault that Supersonic failed to invoice me, this is the 1st for me, never heard of such a thing before!! It was a failure on their part!!! I asked the lady if I could possibly pay of the outstanding amount over two months, R997.51 per month. After a lengthy wait on the phone for her to come back to me she said that whoever she spoke to informed her that my services will be suspended tomorrow, 1st April unless I make the full payment of R1995.02. This is unacceptable, their failure to generate invoices has now become my problem. They can suspend me tomorrow as I do not have R1995.02 to pay in one go. They can also make arrangement to come and collect their router at a time convenient to myself.