Double charging a pensioner

My father who is a pensioner and nearly 90 years old has a Vodacom fibre account and has been complaining that he is being debited more than what he was told when he signed up. I looked at his bank statements and he is being charged R1600 a month for 50 up 50 down fibre connection which is R800. I enquired about this and was told he’s been charged double because he has 2 lines at the same address. This is not true there’s one line and one router. He is being charged double for a line which we know nothing about. A pensioner who is almost 90 being taken advantage of in his fashion is not acceptable