Poor Service zdelivery

I have tried numerously to let Wesbank know my issue to no avail. I bought a car in 2017, i negotiated at the delearship for a no-balloon payment on the car and opted to pay a higher montly premium of almost R 12 000 instead of what was supposed to be R 9 000. I trusted all was well and never looked at my statements. I happened to look at one and i was almost knocked off my chair to see a balloon payment. i requested the contract signed and was even more shocked as my signature is not what was on the contract. I decided to contact Wesbank via calls and email to no avail. they send automated mails and its been 5 months already. i would appreciate a feedback and a solution to this issue.