Disconnecting our services

Autopage is not treating my husband and I right, for tge past 3 months it has been disconnecting our services and reconnecting claiming that they haven't received instalments, but they'd reconnect just after they receive calls from us. This month they hay switched us off altogether and they said that my husband hasn't been paying the reconnection fees, they have been switching us off when the payment has been done and they expect reconnection fees payments. Then they threaten to blacklist my husband if he cancels the contract because of their negligence and uncaring attitude. Whose fault is this?