Change of banking details

I change banks and I emailed teljoy to inform them that my bank details I have changed I email it to Zoliswa on22/10/2015 17:47. they did not replay on the email. so I phone them and I hang on for 10 min and then you get a voicemail that say the person is not evadible. So now my banking details is not change and I must pay now additional cost because they did not do their work. On 05/11/2015 about 9H00 I request teljoy to phone me its 12H00 no one phoned me. I send the Email to Zoliswa and Portia again no one replay to my email.