Very Unhappy with Toyota Finance Services

I’m very disappointed with the service I received from Toyota Finance. I bought my car last year in April and I signed a fixed interest rate contract but around March this year I noticed that the interest rate is variable. I contacted TFS several times via email and they never responded, I only received automatic responses. I contacted them telephonically and they kept on telling me that they will investigate this issue and come back to me and it never happened. Apparently, there were two contracts on their system, a fixed contract and a variable contract and I don’t understand how that is possible. I escalated my matter to my lawyers for advice, they also contacted them via email and they never responded. The Financial Manager from Toyota Kingsmead and the sales lady also confirmed that I signed a fixed interest rate contract but unfortunately they can’t assist me with this issue I must contact TFS. I still have an electronic and hard copy of my contract that was issued on the day I collected my vehicle which highlighted the fixed interest rate I am supposed to pay. This is really frustrating and disappointing to receive such bad service from a big company like Toyota I have been financed by them previously but I never received such a bad service