Absolute incompetence from FNB Home Loans

Do NOT ever buy a house using FNB as a service provider. We were selling our investment property. We signed the offer of acceptance in July 2014. In September at lodging we could not proceed because FNB Home Loans managed to lose our deed (YES, that is possible)!!! Due to this disaster the house only registered in May 2015 after numerous threats from the buyers to cancel. Now after completion FNB is only willing to reimburse interest from Dec 2015. Absolutely ridiculous. Apparently all losses occurred due to FNB's incompetence and negligence is my problem?! So my questions: Is it my fault that I had to pay levies and property taxes each month until May 2015 due to negligence from FNB? Is it my fault that I had no tenants for the 8 months that this was delayed to due FNB's incompetence? Then we were promised by FNB that the cancellation attorneys will be paid by them due to their mistake, to my surprise (should I actually still be surprised?) they will not pay that as well. In short