Unfair Early Termination Fee

We provided FNB with notice on 29 December 2019 of our intention to sell our house. There was no reply from FNB and no one contacted us, other than the automated response. Now that we are cancelling the bind, FNB wants to charge us early termination fees. I will NOT pay fees due to the lack of communication from FNB. We have only ever received terrible service crom the Home Loans department and even on our last, this has not changed. Please rectify this or I will lay a charge with the Banking Ombud.