Debit order Query

I bought a Suzuki Baleno on the 21st of May at Suzuki four ways.

The contract that I signed and agreed on said I will pay R5374,71 and they debited R5399.

I was assisted by the sales person by the name of Richardo.

I sent him a text advising that they debited the wrong amount but he is not answering my text or clearigying anything.

I sent an email to westbank as the service provider but they did not answer.

I need assistance because I did not agree on the money they debited.

Regards, Zanele Mabaso